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1.
Although it is well established that school characteristics (SCH) and socio‐economic status (SES) are associated with academic achievement (ACH), these correlations are not necessarily causal. Because academic achievement shows substantial genetic influence, it is useful to embed such investigations in genetically sensitive designs in order to examine environmental influences more precisely by controlling genetic influence on ACH. In the first study of this kind for academic achievement, data were collected for 1,063 same‐sex pairs of seven‐year‐old MZ and DZ twins for teacher‐assessed ACH, UK statistics on SCH, and parent‐reported SES. Exclusive of genetic influence on school achievement, shared environment (environmental influences that make siblings similar) accounts for 12% of the variance in academic achievement. SCH accounts for 17% and SES accounts for 83% of this shared environmental variance. Exclusive of genetic and shared environmental influence including SCH and SES, nonshared environment (environmental influences that do not make siblings similar) accounts for 19% of the variance in academic achievement. The importance of nonshared environmental influences on academic achievement leads to the question of what these child‐specific experiences might be that are not shared by children in the same family, school, and classroom. 相似文献
2.
Genetic and Environmental Influences on Vocabulary IQ: Parental Education Level as Moderator 总被引：12，自引：0，他引：12
David C. Rowe Kristen C. Jacobson & Edwin J. C. G. Van den Oord 《Child development》1999,70(5):1151-1162
This article examines how parental education level moderates the genetic and environmental contributions to variation in verbal IQ. Data are from 1909 non-Hispanic Whites and African American sibling pairs from the National Longitudinal Study of Adolescent Health, which obtained nationally-based samples of identical (MZ) twins, fraternal (DZ) twins, full and half siblings, cousins (in the same household), and biologically unrelated siblings. In the whole sample, the variance estimate for heritability (h2 = .57, SE = .08) was greater than that for shared environment (c2 = .13, SE = .04). Both heritability and the shared environmental estimate were moderated, however, by level of parental education. Specifically, among more highly educated families, the average h2 = .74 (SE = .10) and the average c2 = .00 (SE = .05). Conversely, among less well-educated families, heritability decreased and shared environmental influences increased, yielding similar proportions of variance explained by genetic and environmental factors, average h2 = .26 (SE = .15), and average c2 = .23 (SE = .07). 相似文献
3.
The theory-of-mind abilities of twins, children with nontwin siblings, and only children were compared to investigate further the link between number and type of siblings and theory-of-mind abilities. Three- to 5-year-old children with nontwin siblings outperformed both only children and twins with no other siblings, twins who also had other siblings outperformed twins who did not, and children with at least 1 opposite-sex sibling outperformed children with only same-sex siblings. Twins performed significantly better when asked about the false beliefs of their twins than they did when asked about the false beliefs of their friends. Results are discussed in terms of potential mechanisms that may account for the twin and sibling effects. 相似文献
4.
Research suggests that sibling–peer connections are important for understanding adolescent problem behaviors. Using a novel behavioral genetic design, the current study investigated peer network overlap in 300 child–child pairs (aged 7–13 years) in 5 dyad types: monozygotic (MZ), dizygotic twins, full siblings (FSs), friend pairs, and virtual twins (i.e., same‐aged, genetically unrelated siblings). Genetic relatedness, sex composition, and age differences contributed to peer overlap in sibling dyads. MZ twins showed the highest overlap (82%), opposite‐sex FS pairs showed the lowest overlap (27%), and friend pairs (48%) were close to the mean (53%). Social contact variables and self‐reported relationship intimacy predicted additional variance in peer overlap. The roles of genotype–environment correlational and shared environmental processes in the sibling–peer connections are discussed. 相似文献
5.
A biometrical analysis of perceptions of family environment: a study of twin and singleton sibling kinships 总被引：2，自引：0，他引：2
D C Rowe 《Child development》1983,54(2):416-423
Biometrical genetic analysis was applied to sibling and twin kinship data on 2 dimensions of perceived home environment. Correlations on 1 dimension, Restrictiveness-Permissiveness, were equal and significant for all kinships: MZ twins, DZ twins, same-sex siblings, and opposite-sex siblings significant for all 4 kinships: MZ twins, DZ twins, same-sex siblings, and opposite-sex siblings (r greater than .40). An E2-E1 biometrical model fitted Restrictiveness-Permissiveness, implying that treatments common to siblings create agreement about perceived environment. As intrapair differences were the same for all 4 kinships under this model, the equal environments assumption of the twin method was supported. In contrast, the Acceptance-Rejection dimension fitted a G-E1 model that makes the assumption that sibling similarity is the result of genetic factors and postulates an absence of shared environmental influences. This finding suggests that this aspect of home environment may depend as much on the child's inherited traits as on actual treatments and is in accord with the genetic analysis of individual traits in that developmentally effective environmental factors do not appear to be common to siblings. 相似文献
6.
To test the hypothesis that the genetic etiology of reading disability differs as a function of IQ, composite reading performance data from 223 pairs of identical twins and 169 pairs of same-gender fraternal twins in which at least one member of each pair was classified with reading disability were subjected to multiple regression analysis (DeFries & Fulker, 1985, 1988). In the total sample, heritability of the group deficit in reading performance (h(g)2) was .58 (+/- .08). However, when the basic regression model was fitted separately to data from twin pairs with average Wechsler (1974, 1981) full scale IQ scores below 100 or 100 and above, resulting estimates of h(g)2 were .43 and .72, respectively, a significant difference (p < or = .03, one-tailed). The results of fitting extended regression models to reading performance and continuous IQ data provide evidence that the genetic etiology of reading disability differs as a linear function of IQ (p < or = .007, one-tailed). These results suggest that IQ is relevant for the diagnosis of reading disability and that environmental influences may be more salient as a cause of reading difficulties in children with lower IQ scores. 相似文献
7.
Petrill SA Deater-Deckard K Thompson LA Dethorne LS Schatschneider C 《Journal of learning disabilities》2006,39(1):48-55
The present study combined parallel data from the Northeast-Northwest Collaborative Adoption Projects (N2CAP) and the Western Reserve Reading Project (WRRP) to examine sibling similarity and quantitative genetic model estimates for measures of reading skills in 272 school-age sibling pairs from three family types (monozygotic twins, dizygotic twins, and unrelated adoptive siblings). The study included measures of letter and word identification, phonological awareness, phonological decoding, rapid automatized naming, and general cognitive ability. Estimates of additive genetic effects and shared environmental effects were moderate and significant. Furthermore, shared environmental effects estimated in twins were generally similar in magnitude to adoptive sibling correlations, suggesting highly replicable estimates across different study designs. 相似文献
8.
In order to compare the pattern of gender differences for cognitive measures in opposite-sex twin pairs to that in independent
samples of twins from same-sex pairs, psychometric test data were obtained from four research-identified samples of children:
(1) 96 pairs of opposite-sex fraternal twins in which at least one member of each pair is reading disabled; (2) 62 pairs of
opposite-sex fraternal twins with no history of reading problems; (3) 167 males and 155 females from same-sex identical and
same-sex fraternal twin pairs in which at least one member of each pair is reading disabled; and (4) a comparison sample of
126 males and 132 females from same-sex twin pairs with no history of reading problems. Results of multivariate analyses indicate
that gender differences for cognitive measures are similar in twin pairs with and without reading disabilities. Moreover,
a highly similar pattern of gender differences occurs for opposite-sex twin pairs who shared both prenatal and early postnatal
influences and for independent samples of children from different families. 相似文献
9.
Little is known about the underlying causes and developmental patterns of stability and change in early reading abilities. In a longitudinal study of twins (n=4,291 pairs), individual differences in reading achievement assessed by teachers using U.K. National Curriculum (NC) criteria showed substantial heritabilities at ages 7, 9, and 10 years (.57-.67) and modest shared environmental influences (.10-.17). Stability in NC scores was primarily mediated genetically. There was also evidence for age-specific genetic influences at each age. Genetic influences on reading are substantial and stable during the elementary school years despite the shift from "learning to read" to "reading to learn." 相似文献
10.
Few family studies of delinquency have focused on siblings. We use a sibling research design to evaluate shared (i.e., family) and unshared environmental influences on delinquency. The 15-22-year-old adolescent siblings were nationally representative, and uniquely, in families of 2 to 4 siblings. No unshared family environmental influences were found for sisters and for mixed-sex siblings, but they may exist for brothers. The data suggested substantial shared environmental and/or shared genetic influences for siblings: the median sibling correlations, averaged over family sizes, were: brothers, r = .30; sisters, r = .28, and mixed sex, r = .21. 相似文献
11.
During childhood and adolescence, increases in heritability and decreases in shared environmental influences have typically been found for cognitive abilities. A sample of more than 2,500 pairs of twins from the Twins Early Development Study was used to investigate whether a similar pattern would be found for science performance from 9 to 12 years. Science performance was based on teacher-assessed U.K. National Curriculum standards. Science at 9 years showed high heritability (64%) and modest shared environmental (16%) estimates. In contrast to the expected developmental pattern, heritability was significantly lower at 12 years (47%) and shared environmental influences were significantly higher (32%). Understanding what these increasingly important shared environmental influences are could lead to interventions that encourage engagement in science throughout the lifespan. 相似文献
12.
Jesse L. Hawke Sally J. Wadsworth Richard K. Olson John C. DeFries 《Reading and writing》2007,20(1-2):13-25
To test the hypothesis that the etiology of reading difficulties may differ for males and females in more severely impaired
samples, reading performance data from monozygotic (MZ), same-sex dizygotic (DZss), and opposite-sex dizygotic (DZos) twin pairs were analyzed using a model-fitting implementation of the DeFries-Fulker (DF) model (Purcell & Sham, 2003, Behavior genetics, 33, 271–278). Five non-independent samples were selected using cut-offs of −1 (N = 737 pairs), −1.5 (N = 654), −2 (N = 468), −2.5 (N = 335), and −3 (N = 198) standard deviations (s) below the mean composite reading score of control twins. Male/female gender ratios for children
with reading difficulties were significantly higher than 1.0 for all five samples and increased as a function of severity
(viz., 1.15, 1.17, 1.40, 1.61, and 1.88, respectively). When the DF model was fit to the data, estimates of heritability (h
g2) and shared environmental influences (c
g2) were not significantly different for males and females in any of the groups. Consequently, the most parsimonious model that
provided a good fit to the data at all five levels of severity equated the heritabilities and shared environmental influences
for males and females, and fixed the DZos coefficient of genetic relatedness at 0.5. Thus, these results provide no evidence for a differential etiology of reading
difficulties as a function of gender in more severely impaired samples, and suggest that the same genetic and environmental
influences contribute to reading difficulties in males and females, irrespective of severity. 相似文献
13.
Previous twin studies of reading disability employed a comparison of concordance rates in identical and fraternal twin pairs
as a test for genetic etiology. Recently, a statistically more powerful multiple regression analysis of twin data has been
formulated to assess the importance of genetic factors in the development of reading difficulties. Application of this analysis
to twin data from the Colorado Reading Project yields definitive evidence for a genetic etiology. Results from this study
suggest that approximately 40 percent of the deficit observed in the disabled readers is due to genetic factors, 35 percent
is due to environmental influences shared by members of twin pairs, and about 25 percent is the result of environmental factors
unique to the individual and/or error variance.
This work was supported in part by a program project grant from the NICHD (HD-11681). 相似文献
14.
In order to assess familial resemblance for measures of reading performance, data from 314 pairs of twins in which at least one member of each pair is reading-disabled [142 monozygotic (MZ) and 172 dizygotic (DZ) twin pairs], 273 matched control pairs (131 MZ and 142 DZ pairs), and their parents were subjected to both correlation and regression analyses. Results indicate that parent-offspring resemblance in families of reading-disabled probands does not differ substantially from that in families of controls. In general, the correlations and regressions for MZ twin pairs are greater than those for DZ twins; thus, individual differences in reading performance are due at least in part to heritable influences. As expected, regression coefficients are consistently larger than correlation coefficients for both parent-offspring and proband-cotwin comparisons in the reading-disabled sample, illustrating that regression analyses are more appropriate than correlations for assessing familial resemblance in selected samples. 相似文献
15.
Behavior problems among children from different family structures: the influence of genetic self-selection 总被引：4，自引：0，他引：4
To examine both genetic and environmental influences on children's behavior problems in households defined by marital status and sibling relatedness, this study applied behavioral genetic methodology to four groups totalling 1524 sibling pairs drawn from 796 households: (1) two-parent full siblings, (2) two-parent half siblings, (3) mother-only full siblings, and (4) mother-only half siblings. Model-fitting procedures found that within-group variation on four subscales from the Behavior Problems Index was best explained by a model including both genetic and shared environmental factors. This model was then fit to the behavior problems means of the four groups. Its successful fit to these mean structures suggested that mean-level differences between groups were explained with the same influences that accounted for within-group variation. Genetic influences accounted for 81% to 94% of the mean-level difference in behavior problems between the two-parent, full sibling and the mother-only, half sibling groups. In contrast, shared environmental influences accounted for 67% to 88% of the mean-level difference in behavior problems between the two-parent, full sibling and mother-only, full sibling groups. The genetic influences are interpreted in terms of genetic self-selection into family structures. 相似文献
16.
J. C. Defries Jim Stevenson Jacquelyn J. Gillis Sally J. Wadsworth 《Reading and writing》1991,3(3-4):271-283
The basic multiple regression model for the analysis of selected twin data (DeFries and Fulker 1985, 1988) was fitted to spelling data from 100 pairs of MZ twins and 71 pairs of same-sex DZ twins tested in the Colorado Reading Project (DeFries, Olson, Pennington and Smith 1991), and to data from 12 pairs of MZ twins and 15 pairs of same-sex DZ twins tested in the London twin study of reading disability (Stevenson, Graham, Fredman and McLoughlin 1984, 1987). Estimates of h
g
2
obtained from analyses of these data suggest that about 60% of the deficit of probands is due to heritable influences in both samples. When a regression model was fitted separately to data from males and females in the combined Colorado and London samples, resulting estimates of h
g
2
were 0.66±0.18 and 0.56±0.19, respectively, a nonsignificant difference. Collaborative analyses of data from additional twin studies of reading disability would facilitate more rigorous tests of hypotheses of differential genetic etiology as a function of group membership. 相似文献
17.
In order to assess the validity of school history information as a diagnostic criterion for reading disability, reading performance data from 304 children with a positive history for reading problems were compared to those from 319 children with a negative school history. These children are members of twin pairs who are participants in the Colorado Reading Project (DeFries 1985). A multivariate analysis of variance of Reading Recognition, Reading Comprehension, and Spelling subtest scores from the Peabody Individual Achievement Test (Dunn and Markwardt 1970) yielded a highly significant (p <0.001) difference between groups for both the multivariate and univariate comparisons. The difference between the unweighted mean scores of the school-history positive and negative groups for Reading Recognition was 2.1 standard deviations. Moreover, when discriminant weights estimated from an independent sample of 140 reading-disabled and 140 control nontwin children were used to reclassify the sample of twins, 75% of those with a positive history for reading problems were classified as being reading disabled and 95% of those with a negative history were classified as unaffected. Thus, results of this study establish the validity of school history information and suggest that such information may have considerable utility for ascertaining samples of reading-disabled children. 相似文献
18.
Brian Byrne Cara Delaland Ruth Fielding-Barnsley Peter Quain Stefan Samuelsson Torleiv Høien Robin Corley John C. DeFries Sally Wadsworth Erik Willcutt Richard K. Olson 《Annals of dyslexia》2002,52(1):47-73
We have initiated parallel longitudinal studies in Australia (Byrne, PI), the United States (Olson, PI), and Norway (Samuelsson,
PI) of identical and fraternal twins who are being tested in preschool for prereading skills, and in kindergarten, first grade,
and second grade for the development of early reading, spelling, and related cognitive skills. Comparisons of the similarities
of identical and fraternal twins will reveal the relative influence of genetic, shared family environment, and nonshared environment
on individual differences at and across different stages of development. Family and twin-specific environmental information
is also being directly assessed through parent questionnaires and observations by testers. Most of the data collected so far
have been from preschool twins (146 in Australia, 284 in the United States, and 70 in Norway). Preliminary analyses for the
preschool cognitive measures showed reliable genetic influences on phonological awareness and several measures of memory and
learning. In contrast, vocabulary, grammar, and morphology showed significant shared environment and negligible genetic effects.
A print knowledge composite showed both genetic and shared environment influence. 相似文献
19.
The genetic and environmental etiologies of sex-typed behavior were examined during the preschool years in a sample of 3,990 three- to four-year-old twin and non-twin sibling pairs. Results showed moderate genetic and significant shared environmental influence for boys and substantial genetic and moderate shared environmental influence for girls. For both boys and girls, twin-specific shared environmental effects contributed to twins' similarity in gender role behavior and accounted for approximately 22% of the shared environmental variance. These findings extend previous research conducted with older samples by showing not only important genetic contributions to gender role behavior but also an important role for shared environment. The inclusion of non-twin siblings showed that some of the shared environmental influence is specific to twins. 相似文献
20.
Chayna J. Davis Valerie S. Knopik Richard K. Olson Sally J. Wadsworth John C. DeFries 《Annals of dyslexia》2001,51(1):231-247
The present study assesses the genetic and environmental etiologies of reading, rapid naming (RN), and their covariation by
fitting multivariate structural equation models to data from 587 twin pairs in which at least one member of the pair exhibited
reading difficulties (low-range) and from 360 control (normal-range) twin pairs who were tested in the Colorado Learning Disabilities
Research Center. Results from a bivariate phenotypic analysis with two hypothesized latent factors, READ and RN, indicated
that the correlation between reading and rapid naming performance for the low-range sample was significantly higher than that
of the normal-range sample. When this model was partitioned to include estimates of genetic, shared environmental, and nonshared
environmental influences, resulting heritability estimates did not differ significantly for the low-range and normal-range
samples for either READ or RN. However, similar to the phenotypic correlation, the genetic correlation between the READ and
RN latent factors could not be equated for the two groups. Thus, the etiology of the relationship between reading performance
and rapid naming may differ for children with reading difficulties and normally-achieving readers. Moreover, these results
support previous findings that the best predictors of reading skills may differ for samples of children with normal reading
levels and those with reading difficulties. 相似文献