Abstract
Autistic traits are influenced by both genetic and environmental factors, and are known to vary geographically in prevalence. But to what extent does their aetiology also vary from place to place? We applied a novel spatial approach to data from two large twin studies, the Child and Adolescent Twin Study in Sweden (CATSS) and the Twins Early Development Study (TEDS) in the UK, to explore how the influence of nature and nurture on autistic traits varies from place to place. We present maps of gene- and environment- by geography interactions that suggest, for example, higher heritability and lower non-shared environmental influence in more densely populated areas. We hope this systematic approach to aetiological interactions will inspire research to identify previously unknown environmental influences on the aetiology of autistic traits.
Competing Interest Statement
Angelica Ronald has received a consultancy fee for writing for the National Childbirth Trust and receives an annual honorarium as joint editor of the Journal of Child Psychology and Psychiatry. H. Larsson has served as a speaker for Evolan Pharma and Shire and has received research grants from Shire; all outside the submitted work.