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1.
In order to assess the etiology of reading disability as a function of mathematics performance, data from 168 monozygotic (MZ) and 127 same-sex dizygotic (DZ) twin pairs in which at least one member of each pair was reading-disabled were subjected to quantitative genetic analyses. MZ and DZ concordance rates for reading disability were computed for different levels of mathematics performance, and reading performance data were fitted to an extension of the basic multiple regression model for the analysis of selected twin data. Results of these analyses suggest that genetic factors may be especially salient as a cause of reading disability in children with borderline deficits in mathematics performance: thus, mathematics performance may be a valid dimension for diagnosing subtypes of reading disability.  相似文献   

2.
In order to test the hypothesis that genetic influences are moreimportant as a cause of reading disability in girls than in boys,composite reading performance data from identical and fraternal twinpairs were analyzed using both concordance and multiple regressionmethods. The sample included 206 identical (99 male, 107 female), 159same-sex fraternal (90 male, 69 female), and 117 opposite-sex fraternaltwin pairs, in which at least one member of each pair had readingdifficulties. Although the difference between the concordance rates forreading disabilities in female identical and same-sex fraternal twinpairs was somewhat greater (65% for identical twins vs.32% for fraternal twins) than the difference in concordance ratesfor boys (68% vs. 39%), loglinear analysis of thesecategorical data revealed that the interaction between sex, zygosity,and concordance was not significant (p > 0.70). Moreover,the heritability of reading disability(h 2 g) estimated from regression analysisof the reading performance data in males was nearly identical to that infemales (h 2 g = 0.58 and 0.59,respectively; p > 0.90). Thus, results of this studyprovide little or no evidence for the hypothesis of greater geneticinfluence on reading difficulties in girls than in boys.  相似文献   

3.
The present study examined the etiology of highreading ability in an overall sample of 350twin pairs in which at least one member of 100pairs (54 MZ, 46 DZ) had a reading compositescore one standard deviation above the sample mean. These highreaders also had significantly higher scoresthan the rest of the sample on Full Scale,Verbal and Performance IQ scores, as well as onmeasures of phoneme awareness, orthographiccoding, phonological decoding, and verbalshort-term memory. The MZ proband-wiseconcordance rate for high group membership wassignificantly higher than the DZ proband-wiseconcordance rate and further behavioralgenetic analyses corroborated that high readingability is partly due to genetic influence(h2 g = 0.55 ± 0.22). Bivariatemultiple regression analyses demonstrated thathigh phonological awareness, orthographiccoding, phonological decoding, and short-termverbal memory skills all share significantcommon genetic influence with high readingability. These results suggest that readingability and its cognitive correlates are on acontinuous distribution, with both extremes ofthe distribution being similarly heritable. They also support the hypothesis that the samecognitive processes that are associated withdyslexia are important for the development ofhigh reading ability.  相似文献   

4.
Reading performance data from 254 pairs of identical (MZ) and 420 pairs of fraternal (DZ) twins, 8.0 to 20.0 years of age, were subjected to multiple regression analyses. An extension of the DeFries-Fulker (DF) analysis (DeFries & Fulker, 1985, 1988) that facilitated inclusion of data from 303 of their nontwin siblings was employed. In addition to providing estimates of heritability, this analysis yields a test of the difference between shared environmental influences for twins versus siblings (Astrom et al., 2011). Results suggest that proband reading deficits are due substantially to genetic factors (.67 ± .07, p < .001), and that shared environmental influences are significantly higher for members of twin pairs than for those of twins and their nontwin siblings (viz., .25 versus .17, p = .02).  相似文献   

5.
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.
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   

7.
Genetic influences on reading are investigated in a sample of 285, 13 year old twins. Using a multiple regression procedure, the heritability of disability (h g 2 ) for Reading Recognition was found to be non-significant. However the h g 2 for spelling disability was found to be 0.58 (P<0.05), after controlling for individual differences in IQ. The twins in this study were an unselected sample from the general population. Therefore it was possible to estimate h g 2 for differing degrees of severity of disability. These analyses showed that for spelling but not for Reading Recognition or Reading Composite, there were substantial genetic contributions to all levels of disability. For indices of Orthographic Coding there were no significant values of h g 2 . In contrast measures of Phonological Coding and Homophone Recognition have consistently high values of h g 2 . More detailed analyses suggested that there were possibly two independent aspects of phonological ability, each influenced by genetic factors.  相似文献   

8.
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   

9.
We explored the genetic background of individual differences in dynamic measures of verbal learning ability in children, using a Dutch version of the Auditory Verbal Learning Test (AVLT). Nine-year-old twin pairs (N = 112 pairs) were recruited from the Netherlands Twin Register. When possible, an older sibling between 10 and 14 years old participated as well (N = 99). To assess verbal learning, non-linear curves were fitted for each child individually. Two parameters were estimated: Learning Speed (LS) and Forgetting Speed (FS). Larger twin correlations in monozygotic (MZ) than in dizygotic (DZ) and sibling pairs for LS and FS indicated the importance of genetic factors in explaining variation in these traits. The heritability estimate (percentage of variance explained by genetic factors) for LS was 43% for both twins and siblings. For FS heritability was estimated at 20% in twins and was slightly higher (30%) in their older siblings.  相似文献   

10.
Neonatal Temperament in Monozygotic and Dizygotic Twin Pairs   总被引：1，自引：0，他引：1  
To determine if neonatal temperament was influenced by genetic factors, temperament was assessed in 316 newborn twins from 47 pairs of monozygotic (MZ) twins, 39 pairs of same-sex dizygotic (DZ) twins, and 72 pairs of opposite-sex dizygotic twins. The neonatal assessment focused on irritability, resistance to soothing, activity level, reactivity, and reinforcement value. Examination of intraclass correlations for MZ and DZ twins and the results of model-fitting analyses indicated that heritability estimates for neonatal temperament were not significantly different from zero, and that there was substantial environmental influence on neonatal temperament. Specific perinatal indicators of risk were found to account for some of the intrapair differences observed for the behavioral variables. It was concluded that there is no clear pattern of genetic influence on temperament in the neonatal period.  相似文献   

11.
Differential genetic etiology of reading disability as a function of IQ   总被引：5，自引：0，他引：5  
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   

12.
The present study examined the phenotypic and genetic relationship between fluency and non-fluency-based measures of reading and mathematics performance. Participants were drawn from the Western Reserve Reading and Math Project, an ongoing longitudinal twin project of same-sex MZ and DZ twins from Ohio. The present analyses are based on tester-administered measures available from 228 twin pairs (age M = 9.86 years). Measurement models suggested that four factors represent the data, namely Decoding, Fluency, Comprehension, and Math. Subsequent quantitative genetic analyses of these latent factors suggested that a single genetic factor accounted for the covariance among these four latent factors. However, there were also unique genetic effects on Fluency and Math, independent from the common genetic factor. Thus, although there is a significant genetic overlap among different reading and math skills, there may be independent genetic sources of variation related to measures of decoding fluency and mathematics.  相似文献   

13.
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   

14.
Previous twin studies have provided evidence for genetic influences on reading disability (RD) or normal reading ability. The existence of subtypes of RD — each with its characteristic cognitive profile — has been suggested. Whether the etiology of the particular subtypes is genetic is uncertain. The present study examined within-pair comparisons of cognitive profiles (with respect to composites of general reading, symbol processing speed and sequential memory) in RD and control twins. Twin profile analysis were applied to these cognitive composites on 120 pairs of RD and control twins. Results showed a greater monozygotic (MZ) than dizygotic (DZ) resemblance in profiles indicating that individual differences in the patterning of cognitive abilities related to reading are genetically influenced.  相似文献   

15.
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   

16.
The genetic and environmental contributions to children's maladaptive behavior are assessed in a sample of 154 twin pairs (77 MZ twin pairs and 77 DZ twin pairs), who range in age from 6 to 11 years. To bridge the strengths of behavioral genetic methods and environmental assessment techniques, we use a multimethod, multimeasure approach to data collection, and analyze the data using behavioral genetic modeling techniques. Results indicate that genetic variation accounts for a majority of the variance in parent-reported child maladaptive behavior (average = 62%). One parent-report measure also suggests a smaller, significant contribution of shared environmental variance. In contrast to the parental ratings, the observational coding and global impressions of parent-twin interactive behavior suggest that shared environment is the primary source of variance accounting for parent and child maladaptive behavior. This is due, in part, to the direct influence one's interactive partner has on the expression of maladaptive behavior in an interactive setting. When controlling for the co-participant's behavior, genetic variation increases and shared environmental variation decreases.  相似文献   

17.
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   

18.
This report presents data on 9-month-old twin pairs (n(MZ)=172; n(DZ)=333) from the Early Childhood Longitudinal Study, demonstrating that the role of genetic variation among infants is trivial and the shared and nonshared environment is substantial in accounting for the observed quality of infant-caregiver relationships. In contrast, maternal reports of temperament were best accounted for by genetic variation and nonshared environmental influences. Interestingly, however, shared environmental effects were documented for observations of temperament. Consistent with a growing database, the current study calls into question the ubiquity of heritability effects in all domains of psychological inquiry. It also bolsters consensus in the field of developmental psychology that shared environmental effects are not as elusive as had once been thought.  相似文献   

19.
A fairly recent definition of reading disability (RD) is that in the form of a hybrid model. The model views RD as a latent construct that is manifested through various observable unexpected impairments in reading-related skills and through inadequate response to intervention. The current report evaluated this new conceptualization of RD from an etiological perspective. The sample consisted of 2,737 twin pairs in 1st through 4th grade (Mage = 8.52) from the Florida Twin Project on Reading. Using twin analyses, results showed that a substantial proportion of genetic variance, a small proportion of shared environmental, and a small proportion of nonshared environmental variance was attributed to the RD factor. Findings suggest that the etiological architecture of RD closely mirrors the structure of the hybrid model of RD.  相似文献   

20.
The main purpose of this study was to describe the relational structure of child twins on the basis of their mothers' representations of their behavior in two everyday settings, at school and in the home. This study looks in particular at dependence on the co-twin and the dominant/dominated relationship in these two life environments. Fifty-seven questionnaires were gathered from mothers of twins three months after the children had begun preschool. A multiple correspondence analysis and an automatic classification of the data pointed out several relational structures of the twin sibling relationship, in contrast to the often stereotyped single representation of twinship. A secondary aim was to associate the observed relational structures with (a) the type of twinship and the sex makeup of the twin pair (b) the mothers' child-raising behaviors, which may or may not tend to turn the twins outward (first short separation of the children before preschool). Contrary to predictions, no particular relational structures could be differentiated on the basis of the type of twinship (monozygotic vs. same-sex dizygotic twins). On the other hand, pairs composed of a boy and a girl exhibited a number of specific characteristics. Parents who were in favor of short separations did not have children who were more co-twin independent in the school environment. However these twins showed a dominant/dominated relationship in the home.  相似文献   

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