Polygamists Avoiding Inbreeding Problems?

In his past research, Mark Leone, a professor of sociology at the University of Maryland, showed that more subtle health effects, including nearsightedness and mental problems, could be seen in some isolated groups in which inbreeding was known to have occurred.

And Bradley notes that a further narrowing of genetic diversity within the group may accompany another practice that has been seen within FLDS — a skewing of the male to female ratio.

"When I did my work in the early '90s, it was pretty close to 50-50," she says. "But increasingly in the last five years, these groups have been sending young boys out of the community. They're essentially getting rid of competition."