This article reviews representative literature concerning pedigrees for myopia, heritability studies on refractive error and the ocular components, and other work relating to genetic factors in myopia development. Low myopia most likely reflects the influences of multiple genes. Some types of high myopia may have monogenic inheritance. Refractive error and the ocular refractive components have heritabilities intermediate between zero and one, as complied from several studies, indicating familial resemblance, but also non-genetic variation. It is likely that both heredity and environment have roles in determining refractive status. An understanding of their respective roles awaits the elucidation of the cellular and anatomical mechanisms of myopia development.