title: Developmental origins of low mathematics performance and normal variation in twins from 7 to 9 years.
abstract: A previous publication reported the etiology of mathematics performance in 7-year-old twins (Oliver et al., 2004). As part of the same longitudinal study we investigated low mathematics performance and normal variation in a representative United Kingdom sample of 1713 same-sex 9-year-old twins based on teacher-assessed National Curriculum standards. Univariate individual differences and DeFries-Fulker extremes analyses were performed. Similar to our results at 7 years, all mathematics scores at 9 years showed high heritability (.62-.75) and low shared environmental estimates (.00-.11) for both the low performance group and the full sample. Longitudinal analyses were performed from 7 to 9 years. These longitudinal analyses indicated strong genetic continuity from 7 to 9 years for both low performance and mathematics in the normal range. We conclude that, despite the considerable differences in mathematics curricula from 7 to 9 years, the same genetic effects largely operate at the two ages.
authors.affiliation: Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, De Crespigny Park, London, United Kingdom. Claire.Haworth@iop.kcl.ac.uk
authors.forename: Claire M A
authors.initials: CM
authors.lastname: Haworth
authors.forename: Yulia
authors.initials: Y
authors.lastname: Kovas
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Petrill
authors.forename: Robert
authors.initials: R
authors.lastname: Plomin
mesh_terms: D002648:Child; D032882:Comprehension; D003479:Curriculum; D004739:England; D005260:Female; D006801:Humans; D007858:Learning; D007859:Learning Disabilities / Q000209:etiology / Q000235:genetics; D008137:Longitudinal Studies; D008297:Male; D008433:Mathematics; D014427:Twins / Q000235:genetics*; D014852:Wales