Human interest in trait inheritance long predates understanding of the modes and mechanisms of inheritance, and as shown by resources included in this discussion, selective breeding alone drove notable early phenotype changes in agricultural species and in dogs. Since the 1970s, the rapid improvement and declining costs of DNA sequencing technologies have enabled collection of whole-genome data from large numbers of individuals and across many species. Comparing these genomes has sometimes revealed specific genetic features strongly associated with biological traits, including elevated risk of specific cancers in individual humans, and the capacity of some, but not all, mammalian species to synthesize vitamin C. Often, though, genomewide association studies (GWAS) in human populations have revealed that genetic disease can be traced not to one genetic change of very large impact, but instead to many changes of individually modest impact on overall disease risk. This discovery that many human diseases are of polygenic origin only heightens the need for large data sets that can drive the discovery of health-relevant variation and ensure that the benefits of such knowledge are accessible to humans worldwide.