Practice question

When pedigree displays only males affected in every generation with direct transmission from father to son along male line, Y chromosome linkage is strongly suspected. Y-linked genes pass exclusively along paternal lineage because only males possess Y and father contributes Y to all biological sons. X-linked recessive would show affected males linked through carrier females and absence of father-to-son transmission. Autosomal modes affect both sexes equally. Mitochondrial transmission requires affected mothers passing trait to all children. Hence all-male, father-to-son vertical pattern indicates holandric inheritance without female involvement.