Familial Studies: Genetic Inferences

Most human characteristics (including behavioral and neurocognitive phenotypes) are influenced to some extent by heritable genetic variation. The concept of heritability, which is a measure of the relative amount of observed phenotypic variance that is attributable to genes, has had a long and controversial history in human genetics. Inference about heritability obtained from familial relationships predated and informed the discovery of the cellular and biochemical mechanisms of inheritance. Our recent ability to obtain complete DNA sequence of individual genomes reveals the full extent of human genetic diversity, and allows for identification of empirical patterns of kinship when family structure is unknown. In this context, the tools of statistical genetics remain essential for quantifying, identifying, and interpreting causal relationships of genetic variation to traits of interest. This article reviews key concepts and controversies in statistical genetics and introduces recent advances in efficient inference from complex pedigrees.