If you've ever done genealogy, you quickly realize that those individuals don't matter. People care most about people that they are descended from -- not their

If you've ever done genealogy, you quickly realize that those individuals don't matter. People care most about people that they are descended from -- not their siblings or other non-lineal ancestors. And while people recognize adoption, they often care more about their blood relatives. Hence, the proliferation of Y-chromosome and mtDNA genetic genealogy.