DNA testing: How African are you?

DNA testing for genealogy has become increasingly popular, as a Newsweek cover story in February attests. Especially attention-getting have been efforts to trace genetic relationships along the male lineage.

The newer "genetic admixture tests" examine DNA from genes inherited from all of a person's grandparents, great-grandparents, and so on. A few of these genes reflect the part of the world where those ancestors lived. Like postcards, they track the movement of people from the lands of their ancestors to their current address.