Background: Twin research has consistently shown substantial genetic influence on individual differences in cognitive ability; however, much less is known about the genetic and environmental aetiologies of school achievement.
Aims: Our goal is to test the hypotheses that teacher-assessed achievement in the early school years shows substantial genetic influence but only modest shared environmental influence when children are assessed by the same teachers and by different teachers.
Sample: 1,189 monozygotic (MZ) and dizygotic (DZ) twin pairs born in 1994 in England and Wales.
Methods: Teachers evaluated academic achievement for 7-year-olds in Mathematics and English. Results were based on the twin method, which compares the similarity between identical and fraternal twins.
Results: Suggested substantial genetic influence in that identical twins were almost twice as similar as fraternal twins when compared on teacher assessments for Mathematics, English and a total score.
Conclusions: The results confirm prior research suggesting that teacher assessments of academic achievement are substantially influenced by genetics. This finding holds even when twins are assessed independently by different teachers.