A Behavioral Genetic Study of the Overlap
Between Personality and Parenting
Frank M. Spinath
University of Bielefeld
Thomas G. O Connor
Department of Child and Adolescent Psychiatry and Social,
Genetic, and Developmental Psychiatry Research Centre,
London
ABSTRACT The current study had three aims. The first was to
examine the covariation between personality of parents and parenting
behaviors. The second aim was to examine the genetic and environmental
influences on parenting behaviors. The third aim was to examine the
extent to which the association between personality and parenting was
mediated by genetic and environmental factors. Personality (Five Factor
Model, NEO-FFI) and parenting data were collected as part of a larger
German study of 300 adult twin pairs (GOSAT). The current paper
analyzes data on a subset of the 300 twin pairs from the GOSAT sample
who were concordant for having children (n 5 98 pairs or 196
Frank M. Spinath, Department of Psychology, University of Bielefeld, Bielefeld,
Germany; Thomas G. O Connor, Department of Child & Adolescent Psychiatry and
Social, Genetic, and Developmental Research Centre, London, United Kingdom.
The research reported in this article was supported in part by a grant from the
German Research Foundation (Deutsche Forschungsgemeinschaft).
We are indebted to the twins for their participation. We d like to thank Alois
Angleitner, Peter Borkenau and Rainer Riemann for their support and Robert Plomin
for helpful comments on an earlier draft of this paper. The study is based on the
German Observational Study of Adult Twins (GOSAT) directed by Angleitner,
Borkenau, and Riemann.
Correspondence concerning this article should be addressed to Frank M. Spinath,
Department of Psychology, University of Bielefeld, P.O. Box 100131, 33501 Bielefeld,
Germany. Fax: [phone]. E-mail: [e-mail]
Journal of Personality 71:5, October 2003.
Blackwell Publishing 2003
786 Spinath & O Connor
individuals). Results indicated modest overlap between personality and
parenting. In addition, univariate behavioral genetic analyses indicated
moderate genetic influence on select parenting dimensions. Results also
indicated that the moderate phenotypic covariation between personality
and parenting was attributed largely to nongenetic factors. Implications
of the findings for research on parenting and personality are considered.
A predominant view in clinical and developmental psychology
research is that parental behavior is a relatively specific, learned
pattern of behavior that reflects a history of relationship influences
and is affected by current stresses and supports, as well as child
characteristics (Belsky, 1984; Conger, Ge, Elder, Lorenz, & Simons,
1994; Cox, Owen, Lewis, & Henderson, 1989). An alternative view,
derived from personality psychology, is that behavior in a parenting
context may not be domain-specific, but instead, reflect general and
stable personality characteristics (e.g., Kochanska, Clark, & Gold-
man, 1997). Alongside environmental hypotheses of the determi-
nants of parental behavior is the further question of the role of
genetic influences. The current study, based on a community sample
of German twins, was designed to test competing theories about the
origins of individual differences of parenting. Specifically, we
examine the covariation between parenting and personality and
the degree to which covariation between personality and parenting is
explained by overlapping genetic and environmental influences.
Parenting and Personality
Numerous investigations connect various forms of psychopathology
with impaired parenting behavior (Downey & Coyne, 1990; Rutter
& Quinton, 1984; Radke-Yarrow, 1991), but considerably less
research has addressed the correlation between normal variation in
personality and parenting. Available findings are somewhat difficult
to interpret given the diverse ways in which both parenting and
personality have been measured, but some similarities are apparent.
For example, Kochanska et al. (1997) found that mothers high in the
personality characteristics of negative emotionality and disagree-
ableness were rated by observers as being more rejecting toward
their children (see also Clark, Kochanska, & Ready, 2000).
Similarly, Belsky, Crnic, and Woodworth (1995) reported that
neuroticism was a robust predictor of a range of observed parenting
behaviors, notably negativity/rejection. A third set of findings, based
Personality and Parenting 787
on questionnaire measures, indicated that a parenting dimension
termed positive support was moderately positively correlated with
each of the five dimensions of personality measured; the overlap
between negative affect and control dimensions of parenting with
personality was less consistent (Losoya, Callor, Rowe, & Goldsmith,
1997).
The phenotypic data reviewed above indicate that there is a link
between parenting and personality, but that it may be modest in
magnitude. A second lesson is that the degree of overlap depends on
the personality and parenting dimensions considered. Specifically,
the most robust connection appears to be between neuroticism or
negative affect and negative/rejecting parenting. What has not
received much attention are the origins of the overlap between
parenting and personality.
Genetic Influences on Parent-Child Relationships
Quality of parent-child relationships is partly influenced by genetic
factors. Evidence of this comes from twin and adoption studies of
young children and adolescents across a range of methodologies
(Lytton, 1977; Deater-Deckard & O Connor, 2000; O Connor,
Hetherington, Reiss, & Plomin, 1995; Plomin, Reiss, Hetherington,
& Howe, 1994). However, nearly all of the studies of genetic
influences on parent-child relationships are child-based designs.
That is, the genetically informative feature of the sample is the
children being parented rather than the parents themselves. Child-
based designs are useful for testing hypotheses concerning   child
effects  models of parenting behavior, but a limitation is that genetic
influences on parenting are measured only indirectly (i.e., via genetic
influences on children s behavior that elicits parenting behaviors).
The inverted design, in which the parents are the twins, is needed in
order to identify direct genetic influences on parenting behavior.
Far fewer investigations use a parent-based design to assess
genetic influences on parent-child relationships. In one of the first
studies of this kind, Plomin, McClearn, Pedersen, Nesselroade, and
Bergeman (1988) reported that perceptions of the current family
environment in a sample of elderly twins was partly heritable. A
small number of studies focus more specifically on parenting, but
report inconsistent results. For example, Kendler (1996) found
moderate evidence of genetic effects on a dimension of parental
788 Spinath & O Connor
warmth, although the influences of environmental factors, including
the effects of a presumed common rearing environment in child-
hood, were dominant for the other two dimensions assessed,
protectiveness and authoritarianism. These findings were partly
replicated, but also contradicted, by Perusse, Neale, Heath, and
Eaves (1994) using the same measure of parenting. In the latter
study, genetic influences were found for all parenting behaviors and
there was no evidence of shared or common rearing environment.
Somewhat different results were reported in a separate study by
Losoya et al. (1997), who found moderate genetic influence on a
measure of positive/supportive parenting; the relative impact of
genetic and environmental variance on a negative control dimension
of parenting was less clear. Although findings concerning the genetic
influence on parents behavior differ across method and measure,
there is some suggestion that genetic factors may be involved.
Regardless of which specific parenting dimension may reflect
genetic influence, it remains to be seen whether or not the nature of
the connection is   direct  or instead mediated through some other
genetically influenced behavior. The hypothesis tested in the current
study is that genetic influence on parenting behavior is mediated via
the genetic effects on personality.
Framework of the Current Study
We sought to integrate the lines of research discussed above in order
to address key questions concerning the origins of parent-child
relationships. Specifically, we reasoned that because there are robust
genetic influences on personality (e.g., Plomin, DeFries, McClearn,
& McGuffin, 2001) and, to a lesser extent, on at least some
dimensions of parenting behavior, then the overlap between
personality and parenting may be partly genetically mediated. The
current study is one of the first to examine the genetic and
environmental influences on the covariation between parenting and
personality.
The parent-based twin design used in this investigation not only
provides a critical test of genetic influence, but also of environmental
influence. Specifically, behavioral genetic designs distinguish be-
tween two types of environmental variance,   shared  and   non-
shared  . Shared or common environmental variance is an index of
experiences that make siblings similar to one another, that is,
Personality and Parenting 789
similarity for nongenetic reasons. In research on adult twins, shared
environment is typically interpreted as the impact of influences
carried over from the family of origin (Kendler, 1996). If this
assumption is correct, then a significant shared environmental
parameter for parenting would suggest that the transmission of
parenting may be partly cultural or familial rather than, or in
addition to, via genetic influences. Furthermore, shared environ-
mental mediation of the correlation between personality and
parenting would be consistent with the view that environmental
influences, which may have been carried over from experiences in the
family of origin, may mediate the connection between the two
dimensions.
Behavioral genetic research also examines nonshared environ-
mental variance, which is attributable to experiences that make
siblings different from one another. In parallel with the above
hypotheses concerning shared environment, the current study is able
to test the hypothesis that personality, parenting and their
covariation are influenced by environmental factors that are unique
to each sibling.
The current study extends existing research in two important
ways. First, we test hypotheses synthesized from two separate lines
of research, namely, that the phenotypic connection between
parenting and personality is explained by genetic as well as
environmental factors. Second, whereas most of the pertinent
investigations to date have been conducted in U.S. samples, the
current study is based on a German community sample of twins.
METHODS
Sample
The German Observational Study on Adult Twins (GOSAT) is a subset
of twins from a larger community twin sample (Spinath, Angleitner,
Borkenau, Riemann, & Wolf, 2002). Monozygotic (MZ) and same-sex
dizygotic (DZ) twins selected to participate in GOSAT ranged in age
from 18 70 years, with an average age of 34 years for the MZ pairs and
35 years for the DZ pairs. There was a predominance of female twin pairs
in both the MZ (75%) and DZ samples (81%). The GOSAT sample was
heterogeneous with respect to socioeconomic status. The current
paper analyzes data on a subset of the 300 twin pairs from the GOSAT
sample who were concordant for having children (n 5 98 pairs or 196
790 Spinath & O Connor
individuals). The subsample with children differed from the sample only
with respect to age (see preliminary analyses). The children of the parents
ranged in age from early childhood through young adulthood. The
number of children ranged from 1 5; approximately three-quarters of the
parents had 1 2 children.
Procedure
GOSAT twins were invited to attend a day-long assessment in a
university laboratory (Spinath et al., 1999). As part of day-long series of
assessments, twins were asked to complete questionnaire measures of
personality and parenting. An extensive battery of observational
measures of personality and temperament were also collected, but are
not part of this report.
Measures
Zygosity. Zygosity of MZ and DZ twins pairs was determined by
genome mapping (Becker et al., 1997) and questionnaire measures
(Oniszczenko, Angleitner, Strelau, & Angert, 1993), with a misclassifica-
tion rate of less than 1%.
Personality: NEO-FFI. Parental personality was measured using the
NEO-FFI (Costa & McCrae, 1989, 1992), a widely used inventory of the
five core personality dimensions known as the five-factor model of
personality (Neuroticism, Extraversion, Openness to Experience, Agree-
ableness, and Conscientiousness). Previous validity of the NEO-FFI on
German samples has been reported (Angleitner, Ostendorf, & John,
1990). Previous analyses of the NEO-FFI on the community sample
replicated prior research and suggested considerable reliability and
validity for the five dimensions (Riemann, Angleitner, & Strelau, 1997).
Parenting: FDEE-R. Parenting behavior was measured using the
FDEE-R, a 31-item self-report measure of parenting with previously
established reliability and validity (Lukesch & Tischler, 1975). The
FDEE-R, which was developed for a German sample, is conceptually
similar to widely used measures in U.S. samples. The measure has four
subscales, Over-protective (14 items; internal consistency (alpha) 5 .76),
Rejecting (6 items; internal consistency 5 .66), Supportive/Indulgent (6
items; internal consistency 5 .68), and Authoritarian (5 items; internal
consistency 5 .68). Parents with high scores on the   over-protective 
scale report that children ought to be watched closely and that parents
need to make sure that they always know what their children do or think
in order to save them from harm. High scores on the   rejecting  scale
Personality and Parenting 791
reflect negative attitudes toward parenthood and children s behavior.
Rejecting parents indicate that having children is occasionally regarded a
burden they find hard to handle. High scorers on the   mild-compliant 
scale propagate mild and lenient behavior towards children and state that
parents should turn a blind eye more often. Finally, high scores on the
  authoritarian  scale indicate the parent s acceptance of physical
punishment (e.g., smacking a disobedient child). Items were rated on a
3-point Likert-type scale. The above factors were based on factor analysis
using varimax rotation (Lukesch & Tischler, 1975). Parenting factor
scores included in the analyses below are based on the items identified to
load on each factor (unit weighted).
Data analysis. The results are presented in three sections. First, we
analyze the intraclass correlations and report univariate behavioral
genetic analyses for the four parenting factors. Second, the phenotypic
correlations between the personality and parenting dimensions are
presented. Third, we report multivariate behavioral genetic analyses on
the covariation between personality and parenting variables for those
pairs of variables that are significantly correlated.
Behavoral genetic analyses. The logic and analyses associated with
partitioning variance of a phenotypic measure into genetic and
environmental sources is described in detail elsewhere (Plomin et al.,
2001). In brief, behavioral genetic models hypothesize three sources of
individual differences. In the case of a twin study, additive genetic
variance (Ga) is implied if the correlation among MZ twin pairs exceeds
that found in DZ twin pairs. Shared environment (Es), or those
environmental factors that function to make siblings similar to one
another, is suggested if the correlation in DZ twins is greater than half
that found in the MZ twin sample. Finally, nonshared environmental
(En) influence indexes those environmental factors that function to make
siblings different from one another. This parameter, which also includes
measurement error, is most clearly seen as 1 the MZ correlation and is
especially implicated if the similarity among twin pairs is small and
nonsignificant, that is, the siblings differ substantially from one another.
Estimates for the above parameters are based on model-fitting
procedures. Following quantitative genetic theory, these models specify
that MZ twins are genetically identical and are therefore correlated 1.0
for additive genetic variance; DZ twins share half of their genes and are
therefore correlated .5. By definition, shared environment is correlated
1.0 because it represents those experiences that function to make siblings
similar for environmental reasons; also by definition, nonshared
environment correlation for all siblings pairs is 0 because it represents
792 Spinath & O Connor
the influences that are unique to each sibling and make siblings different
(see Plomin et al., 2001).
In the bivariate model the sibling cross-covariances, or sibling A s
score on measure 1 with sibling B s score on measure 2, are analyzed. The
bivariate model includes genetic (Ga) as well as the shared (Es) and
nonshared (En) environment estimates mediating the relationship
between the two measured variables. The percentage of the phenotypic
correlation that is due to each of the three sources can be computed by
multiplying the common paths (i.e., the two paths connecting the
measures) and dividing by the phenotypic correlation. The genetic (ga)
and shared (es) and nonshared (en) environmental estimates unique to
each measure are also examined. For example, a significant specific
genetic estimate indicates that there are genetic factors influencing
individual differences in one measure that are independent of the genetic
influences on the second measure.
Several methodological conditions for the genetic models should be
noted. First, in these analyses, we examine only additive genetic variance;
nonadditive (dominant and epistatic) genetic variance was not modeled
because we have little power to discriminate additive and nonadditive
genetic influences and because the twin similarities suggested that for the
most part genetic influences were of the additive variety. Second,
consistent with other studies, parental age and sex were partialed from
the covariances prior to genetic modeling because these variables can
artificially inflate similarity. Third, variance/covariance matrices (based
on double-entered data) were analyzed because they are sensitive to, and
allow tests of, variance differences among groups (Neale & Cardon,
1992). Fourth, both univariate and bivariate behavioral genetic models
make certain assumptions about the nature of the processes being
estimated. Specifically, the models assume no gene environment interac-
tion or assortative mating but the appropriateness of the equal-
environments assumption for the investigated characteristics. In the
current study, we were unable to directly test the validity of these
assumptions. Detailed discussions of the validity of these assumptions are
reported elsewhere (Borkenau, Riemann, Angleitner, & Spinath, 2002;
Loehlin, 1992; Rutter, Silberg, O Connor, & Simonoff, 1999).
The significance of parameters in behavioral genetic models was
examined by fixing the parameter to 0 and reestimating the fit, the
conventional manner used in behavioral genetic research (Neale &
Cardon, 1992). A significant change in the chi-square with 1 df indicates a
significant worsening of the fit and that the parameter should be retained
in the model. For purposes of presentation, however, all estimates are
provided and a parameter is displayed as 0 only if the model estimated
the parameter to be 0. There is wide recognition that the chi-square test
Personality and Parenting 793
for the full model should be accompanied by alternative fit indices and that
each alternative fit index has advantages and limitations. Because a primary
concern in model-fitting is residual variance, the root mean square error of
approximation was chosen to accompany the chi-square test and goodness
of fit results ( Joreskog & Sorbom, 1993). Analyses were run using LISREL,
8th edition ( Joreskog & Sorbom, 1993). Model-fitting results for the
bivariate models are given in the Figure captions.
RESULTS
Preliminary analyses. Prior to behavioral genetic model-fitting, a
series of preliminary analyses were run on the total sample to examine
the connection between zygosity, parent age and sex, and child age
and sex with the parenting variables. Only one significant correlation
(of the 20) was found: child age with Authoritarian parenting
(r 5 .15, po.05). However, this association was not significant
once parental age was partialed. Thus, partialing parental age and sex
prior to fitting behavioral genetic models eliminated the significant
correlation between child age and Authoritarian parenting.
Although all twin pairs completed the parenting questionnaire,
we were primarily interested in those pairs in which both twins were
parents. From a total sample of 300 pairs, 98 pairs were concordant
for having children, 157 were concordant for not having children
and 40 were discordant (data were missing in 5 cases). Subsequent
analyses are based on the twins who were concordant for children
(n 5 196). Pairs who were concordant for having children differed
from those who were concordant for not having children in one
main respect: age. The average age in the former group was 47 years
(range 29 69), whereas the average age in the latter group was 25
years (range 18 67). As suggested by the ranges, the difference was
accounted for by the absence of relatively young parents in the
sample. Importantly, there were no significant differences between
the two groups in any of the 4 parenting or 5 personality measures
once age was covaried.
Univariate genetic analyses. Prior to examining the genetic and
environmental sources of covariance between personality and
parenting, it was first necessary to examine the univariate behavioral
genetic results for each dimension. Behavioral genetic analyses of the
personality data in GOSAT have been previously reported
794 Spinath & O Connor
(Borkenau, Riemann, Angleitner, & Spinath, 2001). As is typically
found for self-reported personality traits, additive genetic factors
(h2) explained about a third of the phenotypic variance, whereas
shared environmental factors (c2) across the dimensions of the five-
factor model were only modest (average c2 across traits 5 .13).
Average peer reports which were available for the GOSAT
participants indicated genetic influences on personality of similar
magnitude as self-reports (average h2 across traits 5 .39), yet
indicated virtually no environmental effect of the shared variety.
Interestingly, aggregated video-based trait ratings of actual behavior
suggested somewhat stronger shared environmental influences than
typically found in questionnaire studies. However, it is important to
note that the data on the current study are a subset of twins from the
larger sample, that is, those twin pairs with children. The
correlations between twins for the personality and parenting
dimensions are displayed in Table 1.
For the parenting variables, consistent with the hypothesis of
genetic influence, the correlation between MZ twins was generally
greater than that for DZ twins. The magnitude of differences was
substantial e.g., for two scales the MZ correlation was greater than
twice the DZ correlation with the single exception of Rejecting. In
addition, shared environment is implicated for all factors in which
the DZ correlation is moderate and similar to that found in the MZ
sample. Finally, given that the MZ correlation is substantially lower
than unity, nonshared environment is implicated.
The personality correlations for the twin pairs concordant for
children are also displayed in Table 1. The correlations are generally
similar to the larger sample from which they were drawn, although
there is a tendency for the MZ twin correlation to be somewhat
lower in this subsample. The same pattern was observed in the peer-
reported data on personality for this subsample (see Riemann et al.,
1997, for details on peer-reported personality).
The model-fitting for the measures of parenting, displayed in
Table 2, confirm the impressions from the correlational data.
Specifically, significant and moderate genetic influence was found
for Over-protectiveness, Supportive/Indulgent and Authoritarian
parenting; no genetic effect was found for Rejecting. Conversely,
sibling similarity could be attributed to environmental factors only
for Rejecting. For each parenting dimension, nonshared environ-
mental variance (plus measurement error) was substantial. Using
Personality and Parenting 795
Table 1
Intra-class Correlations in MZ and DZ Twins: 5 Personality Factors and
4 Dimensions of Parenting
Measure MZ DZ
Personality
Neuroticism .26 .17
Extraversion .35 .27
Openness .46 .42
Agreeableness .22 .12
Conscientiousness .41 .37
Parenting Behavior
Over-protective .48 .27
Rejecting .26 .22
Supportive/Indulgent .33 .12
Authoritarian .43 .16
Note: For MZ twins, the N is 94 (i.e., 47 twin pairs); for DZ twins, the N is 80 (i.e.,
40 pairs) for the personality measures and 86 (i.e., 43 pairs) for the parenting
measures. The above correlations are based on intra-class correlations using the
double-entry procedure (see text).
1 Cronbach s alpha to estimate the magnitude of the error
component for each scale, nonshared environmental influences (e2)
explained between 21 per cent (Authoritarian) and 42 per cent
(Rejecting) of the reliable phenotypic variance. The model-fitting
information provided in Table 2 indicates that each model provided
a satisfactory fit to the data.
Overlap between personality and parenting behavior. Correlations
between the five personality factors and the four dimensions of
parenting are displayed in Table 3. The correlations presented are
those based on double-entered data among the twin pairs
concordant for having children; the significance of the correlations
was adjusted for the correct (i.e., non-double-entered) sample size.
The patterns of correlations did not differ significantly according to
zygosity, parent or child sex, or parent or child age. In addition, the
pattern of correlations was very similar to, and not significantly
different from, the pattern observed in the total sample (i.e., the
sample that included twins with and without children). Overall,
although there were modest to minimal correlations between
796 Spinath & O Connor
Table 2
Model Fit Results, Estimates (Standard Errors), and Standardized
Variance Estimates from Univariate Genetic Analyses of Parenting
Variables
LISREL Standardized
Model Fitting Results Estimates Estimates
w2/df GF RMSEA Ga Es En h2 c2 e2
Over-Protectiven 0/0 1 0 .73 .28 .81 .42 .06 .52
(.34) (.70) (.09)
Rejecting 2.79/4 .95 0  .53 .94  .24 .76
 (.12) (.07)
Supportive/Indulgent .36/2 .99 0 .58  .84 .32  .67
(.12)  (.08)
Authoritarian 3.7/2 .97 .1 .63  .67 .48  .53
(.09)  (.07)
Note: GF 5 Goodness of Fit index; RMSEA 5 root mean square error of
approximation; Ga 5 additive genetic estimate; Es 5 shared environment estimate;
c2 5 shared environmental variance; e2 5 nonshared environmental variance.
*Model run allowing variances to differ between MZ and DZ pairs.
personality and parenting measures, the overlap that did exist is
consistent with prior studies. Specifically, the effect size of the
association between Neuroticism and Rejection (r 5 .22) was small,
as was the association between Openness and Over-protectiveness
(r 5 .23). The complete personality X parenting dimension matrix
is reported in Table 3, although specific hypotheses were not offered
for each correlation. In fact, of the parenting dimensions assessed,
only Rejection was at least modestly correlated with more than one
personality dimension. Given the correlation results, there is reason to
examine genetic and environmental mediation more closely in the case
of Neuroticism and Rejecting, and Openness and Over-protectiveness.
Multivariate behavioral genetic analyses. Given the phenotypic
correlations, multivariate behavioral genetic analyses were needed to
explain genetic and environmental sources of (significant) covar-
iance between personality and parenting in two cases: Neuroticism
and Rejecting, and Openness and Over-protectiveness. The covar-
iance matrices used in the model-fitting are reported in Table 4.
Personality and Parenting 797
Table 3
Phenotypic Correlations Between Personality and Parenting
Personality: NEO-FFI
Agree- Conscien- Extra- Neuro- Open-
ableness tiousness version ticism ness
Parenting
Over-Protective .02 .07 .09 .00 .23n
Rejecting .11 .15 .17 .22n .04
Supportive/Indulgent .02 .04 .08 .09 .10
Authoritarian .10 .05 .01 .02 .05
n
Note: The above correlations are based on double-entered data. po.05.
Estimates from the bivariate model fitting results are displayed in
Figures 1 and 2.
For Neuroticism and Rejecting, the results indicate that virtually
all of the covariance was mediated by nonshared environmental
influences. Because the estimates in the figures are standardized,
multiplying the paths from the same genetic or environmental
factor and summing across Ga, Es, and En reproduces, within
rounding error, the observed phenotypic correlation. Thus,
(.17n.20)1(.39n.47) 5 .21 (the observed phenotypic correlation is
.22). Furthermore, 86% (i.e., .18/.21) of the phenotypic correlation
is explained by nonshared environmental influences. The absence of
significant genetic mediation between the two dimensions is
explained by the relative absence of genetic influence on either
construct.
Figure 1 also illustrates the genetic and environmental influences
unique to personality and parenting. As expected from the
correlations and univariate analyses, there was no genetic influence
unique to Neuroticism or Rejecting parenting, that is, what little
genetic influence there was on rejecting parenting was shared with
Neuroticism, and vice versa. There were, however, significant shared
and nonshared environmental influences unique to each construct. It
is particularly interesting that both dimensions were strongly
influenced by shared environment, but that the shared environ-
mental influences were unique to each dimension. In other words,
the environmental factors that made siblings similar in Neuroticism
798 Spinath & O Connor
Table 4
Cross-Sibling Correlations Between Overlapping Dimensions of
Personality and Parenting
Rejecting and Neuroticism
Rejec- Neuro- Rejec- Neuro-
ting ticism ting ticism
TwinA TwinA TwinB TwinB
MZ Twins
Rejecting TwinA 1.40
Neuroticism TwinA .27 .78
Rejecting TwinB .30 .12 1.40
Neuroticism TwinB .12 .15 .27 .78
DZ Twins
Rejecting TwinA 1.05
Neuroticism TwinA .15 .93
Rejecting TwinB .25 .14 1.05
Neuroticism TwinB .14 .16 .15 .93
Over-protectiveness
and Openness
Over-pro- Open- Over- Openness
tective ness protective TwinB
TwinA TwinA TwinB
MZ Twins
Over-protective TwinA 1.29
Openness TwinA .24 .86
Over-protective TwinB .70 .25 1.29
Openness TwinB .25 .40 .24 .86
DZ Twins
Over-protective TwinA .84
Openness TwinA .14 .65
Over-protective TwinB .19 .15 .84
Openness TwinB .15 .27 .14 .65
Note: Diagonal elements are variances Variances and correlations are based on
double-entry procedure. The N s for the univariate analyses of parenting and
bivariate analyses differ slightly because of missing data (o10%).
were different from those that made siblings similar in their rejecting
parenting. Finally, the model statistics indicate that the estimates
provided a reasonable fit to the data.
Personality and Parenting 799
Ga
Es En
.20
.39
0 0
.47
.17
Rejecting
Neuroticism
0
0 .46 .78 .40 .76
ga es en ga es en
Figure 1
Standardized estimates from the bivariate behavioral genetic
analyses of parental Rejection and Neuroticism, w2(6) 5 5.04, ns;
RMSEA 5 0, GFI 5 .95. For reasons of simplicity, the data were recoded
so that phenotypic correlations across twin groups were positive.
Although the paths to a common factor (i.e., Ga, Es, or En) are fixed to
be equal in the model, the standardized estimates reported in the
Figure differ slightly because of variance differences between the
personality and parenting variables.
Although the phenotypic correlation between Openness and
Over-protectiveness is essentially identical to that found for
Neuroticism and Rejecting parenting, the sources of this covariance
are different. Figure 2 illustrates that the only significant source of
covariance between the two constructs was shared environment
(.43n.51 re-creates, within rounding error, the observed phenotypic
correlation of .23). That is, experiences that made siblings similar in
Openness also made siblings similar in their tendency to be Over-
protective in their parenting. The experiences did not overlap
entirely, however, as suggested by the significant unique shared
environmental parameter for Openness. Interestingly, the absence of
800 Spinath & O Connor
Ga
Es En
0
0
.43 .51
0
0
Overprotective
Openness
0
.55 0 .71 .44 .74
ga es en ga es en
Figure 2
Standardized estimates from the bivariate behavioral genetic
analyses of parental Over-protectiveness and Openness, w2(7) 5 4.12,
ns; RMSEA 5 0, GFI 5 .96. For reasons of simplicity, the data were
recoded so that phenotypic correlations across twin groups were
positive. Although the paths to a common factor (i.e., Ga, Es, or En) are
fixed to be equal in the model, the standardized estimates reported
in the Figure differ slightly because of variance differences between
the personality and parenting variables.
significant nonshared environmental mediation indicates that
experiences that made siblings different in Openness were not the
same as those that made siblings different in Over-protectiveness.
The genetic and environmental influences specific to Openness
and Over-protectiveness (reflected in the Ga, Es, and En parameters)
were also anticipated by the correlations and univariate results.
Specifically, the significant genetic influence on Over-protectiveness
was not shared with Openness, as the latter was little influenced by
genetic influences. Nonshared environmental factors did influence
each dimension to a substantial degree and, as noted above, were
Personality and Parenting 801
unique to each construct. Finally, as suggested by the fit statistics,
the estimates provided an acceptable fit the to the data.
DISCUSSION
The influence of personality and, in particular, the theory of
personality included in the current measurement approach, is
credited with explaining a wide range of behaviors in interpersonal
situations. Indeed, the larger GOSAT study illustrates how many
subtle interpersonal behaviors are influenced by personality
variables (Borkenau et al., 2001; Borkenau, Riemann, Spinath, &
Angleitner, 2000). In a parallel manner, considerable importance is
placed on parenting behavior, and particularly the dimensions
assessed in the current study. To date, few researchers have
investigated the intersection of personality and parenting. We
applied a twin study method to assess the degree to which
personality and parenting behavior covaried, and the extent to
which this overlap could be explained by shared genetic and
environmental factors. The central findings were a) individual
differences in parenting behaviors were influenced by both genetic
and environmental factors, with the exception of Rejecting
parenting, which showed no genetic influence; b) there were
relatively isolated but predictable connections between personality
and parenting behaviors; and c) the covariance between personality
and parenting dimensions was mediated by environmental influences
which were of the shared variety in the analysis of over-protective
parenting and Openness and of the unshared variety in the analysis
of rejecting parenting and Neuroticism.
Genetic Influences on Parenting
There is an increasing appreciation that genetic influence extends
beyond traditional trait-like measures of behavior, such as
personality, to more dynamic, interpersonal behaviors, such as
family interactions (O Connor, Deater-Deckard, & Plomin, 1998).
The current study extends research of this type to a community
sample of adult German twins. Moderate genetic influence was
observed for Over-protectiveness, Authoritarianism, and Suppor-
tive/Indulgent parenting; no genetic effect was found for rejecting
parenting.
802 Spinath & O Connor
Linking the current findings with previous studies is not
straightforward, as there is considerable variation in the kinds of
parenting behaviors assessed and results reported. Indeed, even
studies using identical measures of parenting have reported
conflicting findings (cf. Kendler, 1996 and Perusse et al., 1994).
Nonetheless, the findings that the three parenting dimensions noted
above did show moderate genetic influence is generally consistent
with existing data.
It is not possible to determine the degree to which the
discrepancies observed between the current findings and those from
previous studies can be attributed to a range of plausible
methodological reasons, including measures, design, and culture.
Further research and a greater homogenization among methodol-
ogies is clearly needed to resolve outstanding divergences in this
relatively new line of investigation. However, it is noteworthy that
each of the studies conducted to date suggests that genetic influences
play some role in parenting behavior. This is an important finding
with substantial implications for research on the mechanisms
explaining the environmental roots of individual differences in
children s behavior and psychopathology.
Alongside the genetic findings are the equally important findings
concerning environmental influence. A particularly striking finding
in this regard is the absence of any genetic influence and the presence
of shared environmental influence on parental Rejecting. To the
extent that shared environmental influence can be interpreted as the
impact of environmental influences carried over from childhood
the period in which environmental influences were strongly shared
by siblings these data provide evidence supporting a cultural/
familial transmission of harsh and rejecting parenting and the long-
term consequences of early experiences on parenting behavior in
adulthood. A unique feature of the current study is that, by
accounting for genetic factors directly, we were able to demonstrate
that individual differences in parenting are at least partly mediated
by nongenetic influences. These results support recent findings
suggesting how intergenerational links in parent-child relationship
quality might be environmentally mediated (Belsky, Jaffee, Hsieh, &
Silva, 2001; Waters, Merrick, Treboux, Crowell, & Albersheim,
2000) and that key features of the parent-child relationship, such as
attachment, are largely influenced by shared environment rather
than by genetic factors (O Connor & Croft, 2001).
Personality and Parenting 803
Overlap Between Personality and Parenting
The degree of separation between personality and parenting found
in this study is noteworthy and generally consistent with previous
reports. Where there was overlap, it was between negative, irritable,
or hostile parenting behaviors and personality features. Parallel
findings were noted by U.S. investigators using very different
methods and measures (Belsky et al., 1995; Kochanska et al., 1997).
One connection not found previously was that between over-
protective parenting and the Openness personality factor. The
inverse association between these two constructs is readily inter-
pretable as a tendency for individuals who are themselves not open
to experiences to restrict the behaviors or intrude on the activities of
their children. Although the Openness personality factor has not
received attention in the parenting literature, there are obvious
conceptual similarities with family environmental measures used in
developmental research, such as in the HOME inventory (Plomin et
al., 2001). For example, high scorers on Openness to Experience
typically pursue intellectual interests for their own sake, are open-
minded about unconventional ideas, and enjoy philosophical
arguments. They are willing to try different activities or go new
places. In addition to the readiness to reexamine social, political,
and religious values, they have an active fantasy life and a deep
appreciation for art and beauty (Costa & McCrae, 1992). It has been
demonstrated empirically that Openness to Experience can be
judged by unacquainted observers on the basis of people s living or
working environments with high accuracy (Gosling, Ko, Mannarelli,
& Morris, 2002).
Parenting behavior therefore stands out as an important
behavioral variable that is only modestly associated with person-
ality, at least in non-clinic samples and within the normal range of
functioning. A modest overlap between personality and quality of
parent-child relationships is also consistent with dynamic, bidirec-
tional formulations of parent-child relationships that underscore the
interactive effects of parental personality and child characteristics in
eliciting parental behavior (Clark et al., 2000). A corollary of the
distinctiveness of personality and parenting behavior is that there
may be substantial differences in their etiology, although this is yet
to be systematically examined. Our understanding of the develop-
ment of personality is well advanced (Caspi, 1997); further research
804 Spinath & O Connor
on the developmental origins of parenting is needed in order to test
this hypothesis more directly.
To our knowledge, this is the first investigation of the genetic and
environmental mediation of personality and parenting. Although the
findings must be considered preliminary and in need of replication,
they raise important questions about the nature of parenting risks and
the intergenerational transmission of personality and psychopathology
from parent to child. Several specific findings deserve attention. First,
the covariance between rejecting parenting and Neuroticism was
mediated almost entirely via nonshared environmental experiences.
That is, experiences associated with (subsequent) sibling differences in
the twins rejecting parenting overlapped with those that gave rise to
differences in Neuroticism. This finding may be especially important
for understanding how parental personality problems and poor
parenting jointly influence children s psychological development.
Rejecting, hostile parenting, which is implicated as a feature of
antisocial personality disorder (American Psychiatric Association,
1994; see also Capaldi & Patterson, 1991), has long been associated
with a wide range of behavioral and emotional problems in children
(Patterson, Reid, & Dishion, 1992). These results suggest that
personality problems and poor parenting may co-occur for similar
reasons and, furthermore, that their effects (inter- and intragener-
ationally) may be environmentally mediated.
A second example of the overlap between personality and parenting
behavior also suggested a primarily environmental mediation, Open-
ness and Over-protectiveness. In this case, experiences that made
siblings similar to one another in personality also made them similar in
parenting. The magnitude of the shared environmental mediation
between the two constructs is relatively uncommon in multivariate
genetic studies of adult samples and suggests that the particular shared
experiences may pre-date parenthood. Experiences that may make
siblings similar on (lack of) Openness to Experience and Over-
protective in their stance toward their own children may derive from
the family of origin or other shared settings, such as peer culture or
other social settings (e.g., neighborhood).
Limitations
Interpretation of the findings must be viewed in the context of its
limitations. Perhaps the most important limitation is the small
Personality and Parenting 805
sample size. Although the sample of twins is slightly larger than used
in parallel studies (e.g., Losoya et al., 1997), we had limited power to
detect anything but relatively large effects. The limitation was offset,
to some degree, by the novelty and importance of the research
questions. Moreover, given that the subsample of twins who were
concordant for having children did not differ from the larger sample
from which they were drawn with the exception of being slightly
older it would appear that the findings obtained may not be
substantially biased.
A further limitation, and one that is common to many behavioral
genetic investigations, is that we are unable to identify which
environmental influences are implicated in the models above. By
covarying genetic effects, behavioral genetic designs provide the
most powerful evidence of environmental factors, but additional
research is needed to identify specific environmental factors and
their mode of influence (i.e., by making siblings similar to or
different from one another). Third, the same individuals provided
data on personality and parent-child relationship quality. As a
consequence, it is possible that shared method variance may explain
some of the results, such as the overlap of nonshared environmental
variance connecting rejecting parenting and Neuroticism. Finally,
the meaning or source of shared environment cannot be identified
from this study. Shared environmental variance in studies of adults
is usually interpreted as a carrying forward of effects from childhood
because siblings share environments to a substantially greater extent
as children than they do as adults. Nevertheless, we do not have
direct evidence supporting a family of origin interpretation to the
shared environmental variance components.
The current study highlights the need to test hypotheses spawned
from crossing personality and developmental psychology and
genetic and environmental explanations of individual differences in
behavior. The findings reveal important gaps in research and theory
in separate but complementary fields within psychology, and may
foster further collaborative research approaches.
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