title: A longitudinal genetic study of vocabulary knowledge in adults.
abstract: Vocabulary test scores were obtained from a total of 997 adults, all twins or a sibling of twins in this study. Some (N = 217) individuals were tested twice, around 6 years apart. Heritability varied from 50% at the first test occasion to 63% at the second test occasion. The correlation of scores across time was.74. Structural equation modelling showed that stability in vocabulary knowledge over time can largely (around 76%) be explained by genetic factors. Part of the non-shared environmental variance was stable over time also. Any influence from shared environmental factors could not be detected. Results were similar for the two sexes, except that males generally outperformed females. Results were also similar for two age cohorts, except that the older cohort generally outperformed the younger cohort.
authors.affiliation: Department of Biological Psychology, Vrije Universiteit Amsterdam, the Netherlands. SM.van.den.Berg@psy.vu.nl
authors.forename: Stéphanie M
authors.initials: SM
authors.lastname: van den Berg
authors.forename: Daniëlle
authors.initials: D
authors.lastname: Posthuma
authors.forename: Dorret I
authors.initials: DI
authors.lastname: Boomsma
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D005260:Female; D005838:Genotype; D006801:Humans; D007807:Language Tests / Q000706:statistics & numerical data*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D014427:Twins / Q000235:genetics / Q000523:psychology*; D014429:Twins, Dizygotic / Q000235:genetics / Q000523:psychology; D014430:Twins, Monozygotic / Q000235:genetics / Q000523:psychology