Why we need families in genomic research on developmental psychopathology

BACKGROUND: Fundamental questions about the roles of genes, environments, and their interplay in developmental psychopathology have traditionally been the domain of twin and family studies. More recently, the rapidly growing availability of large genomic datasets, composed of unrelated individuals, has generated novel insights. However, there are major stumbling blocks. Only a small fraction of the total genetic influence on childhood psychopathology estimated from family data is captured with measured DNA. Moreover, genetic influence identified using DNA is often confounded with indirect genetic effects of relatives, population stratification and assortative mating. METHODS: The goal of this paper is to review how combining DNA‐based genomic research with family‐based quantitative genetics helps to address key issues in genomics and push knowledge further. RESULTS: We focus on three approaches to obtaining more accurate and novel genomic findings on the developmental aetiology of psychopathology: (a) using knowledge from twin and family studies, (b) triangulating with twin and family studies, and (c) integrating data and methods with twin and family studies. CONCLUSION: We support the movement towards family‐based genomic research, and show that developmental psychologists are particularly well‐placed to contribute hypotheses, analysis tools, and data.