| Paternal Inheritance |
The lack of recombination means that the entire non-recombining portion of the Y is passed intact from father to son. A male shares the same Y chromosome with his father, paternal grandfather, paternal great-grandfather, and so on. (Fig. 2). Researchers can establish paternal genetic relationships by comparing small differences (polymorphisms) between modern Y chromosomes. The identification of genetic markers such as single nucleotide polymorphisms (SNPs) and indels (insertions and deletions) in the non-recombining regions of the Y provides a tool to study population structure and history, genealogy, and human evolution. Because these regions do not recombine they change very slowly, so they may be useful in identifying stable paternal lineages over thousands of years. Mutations occasionally occur in this DNA, however, which are then inherited down the paternal line.