Heritability in the genomics era — concepts and misconceptions

Abstract

Heritability, the proportion of variation in a particular trait that is attributable to genetic factors, is a fundamental parameter in genetics. First introduced by Sewall Wright and Ronald Fisher nearly a century ago, it is key to the response to selection in evolutionary biology and agriculture, and to the prediction of disease risk in medicine. Heritability is not necessarily constant in a population. Changes in the method of measurement, environmental change and the effects of migration, selection and inbreeding all can alter heritability. The use of high-density genetic marker technologies allows novel estimation methods of heritability, for example, estimation in unpedigreed populations and estimation within families — free of assumptions about variation between families. The estimation of heritability for new phenotypes — those that can be measured with recently developed technologies — provides knowledge about the nature of between-individual differences in core biological processes. For example, amounts of gene expression, brain scanning measurements, the length of telomeres and biochemical compounds measured by mass spectrometry show substantial heritability. Heritabilities are often surprisingly large and at present there is no consensus theory to explain why heritabilities have the values they do. Fortunately, the incredible pace of gene–phenotype discoveries in many species will allow new insights to these questions in the near future.