This study examines the genetic and environmental etiology underlying the development of oral language and reading skills, and the relationship between them, over a long period of developmental time spanning middle childhood and adolescence. It focuses particularly on the differential relationship between language and two different aspects of…

The genetic effects on individual differences in reading development were examined using genome-wide complex trait analysis (GCTA) in a twin sample. In unrelated individuals (one twin per pair, n = 2,942), the GCTA-based heritability of reading fluency was ~20%-29% at ages 7 and 12. GCTA bivariate results showed that the phenotypic stability of…

Purpose: The authors examined the longitudinal stability of genetic and environmental influences on children's productive language sample measures during the early school-age years. Method: Twin study methodology with structural equation modeling was used to derive univariate estimates of additive genetic (A), shared environmental (C), and…

Although evidence suggests that individual differences in reading and mathematics skills are correlated, this relationship has typically only been studied in relation to word decoding or global measures of reading. It is unclear whether mathematics is differentially related to word decoding and reading comprehension. In the current study, the…

Variability in achievement across learners is a hallmark of second language (L2) learning, especially in academic-based learning. The Twins Early Development Study (TEDS), based on a large, population-representative sample in the United Kingdom, provides the first opportunity to examine individual differences in second language achievement in a…

Purpose: Researchers have previously shown that individual differences in measures of receptive language ability at age 12 are highly heritable. In the current study, the authors attempted to identify some of the genes responsible for the heritability of receptive language ability using a "genome-wide association" approach. Method: The…

This study used a cross-lagged twin design to examine reading achievement and independent reading from 10 to 11 years (n = 436 twin pairs). Reading achievement at age 10 significantly predicted independent reading at age 11. The alternative path, from independent reading at age 10 to reading achievement at age 11, was not significant. Individual…

We examined the Simple View of reading from a behavioral genetic perspective. Two aspects of word decoding (phonological decoding and word recognition), two aspects of oral language skill (listening comprehension and vocabulary), and reading comprehension were assessed in a twin sample at age 9. Using latent factor models, we found that overlap…

Purpose: To examine the etiology of the relationship between preschool speech and language, and later reading skills. Method: One thousand six hundred seventy-two children from the Twins Early Development Study (B. R. Oliver & R. Plomin, 2007) were given a comprehensive speech and language assessment at 4 1/2 years. Reading was assessed at 7, 9,…

Background: Studies have suggested genetic and environmental influences on overall level of early reading whereas the larger reading literature has shown environmental influences on the rate of growth of early reading skills. This study is the first to examine the genetic and environmental influences on both initial level of performance and rate…

Purpose: In the 2nd decade of life, language skills expand in both quantitative and qualitative ways. The etiology of these new skills and the relationships among them have been little explored. Method: Taking advantage of widespread access to inexpensive and fast Internet connections in the United Kingdom, we administered four Web-based measures…

Background: Our previous investigation found that the same genes influence poor reading and mathematics performance in 10-year-olds. Here we assess whether this finding extends to language and general cognitive disabilities, as well as replicating the earlier finding for reading and mathematics in an older and larger sample. Methods: Using a…

Background: It is widely believed that there are reciprocal links between reading achievement and reading exposure: children who read more do better at reading, and reading achievement itself promotes reading. We tested the hypotheses that these links arise because children's genetically influenced reading performance is correlated with their…

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…

Multivariate genetic analysis was used to examine the genetic and environmental aetiology of the interrelationships of diverse linguistic skills. This study used data from a large sample of 4 1/2-year-old twins who were tested on measures assessing articulation, phonology, grammar, vocabulary, and verbal memory. Phenotypic analysis suggested two…