DNA ancestry tests reveal roots — maybe

SAN FRANCISCO – Curious about their roots, consumers are spending tens of millions of dollars each year getting their DNA tested and then proclaiming they are one-quarter Irish, 22 percent Scandinavian or 14 percent American Indian.
These pie charts of ethnicity make for great water-cooler conversation. But what about the science? Experts say it is still in its infancy, can reinforce stereotypes and sometimes is flat-out wrong.