Y chromosome
Human Y chromosomes are male-specific sex chromosomes; nearly all humans that possess a Y chromosome will be morphologically male. Although Y chromosomes are situated in the cell nucleus and paired with X chromosomes, they only recombine with the X chromosome at the ends of the Y chromosome; the remaining 95% of the Y chromosome does not recombine. Therefore, the Y chromosome and any mutations that arise in it are passed on from father to son in a direct male line of descent. This means the Y chromosome and mtDNA share specific properties.