Holandric genes are genes situated in the nonhomologous region of the Y chromosome. Holandric genes condition phenotypes that emerge only in men since individuals of the female sex do not present in their X chromosomes genes from the nonhomologous portion of the Y chromosome (existent only in men). A widely known holandric gene is the one that conditions hypertrichosis pinnae (hair in the ears), a phenotype inherited from fathers to sons through the Y chromosome.