Few Risks Seen To the Children Of 1st Cousins (Published 2002) (2024)

Contrary to widely held beliefs and longstanding taboos in America, first cousins can have children together without a great risk of birth defects or genetic disease, scientists are reporting today. They say there is no biological reason to discourage cousins from marrying.

First cousins are somewhat more likely than unrelated parents to have a child with a serious birth defect, mental retardation or genetic disease, but their increased risk is nowhere near as large as most people think, the scientists said.

In the general population, the risk that a child will be born with a serious problem like spina bifida or cystic fibrosis is 3 percent to 4 percent; to that background risk, first cousins must add another 1.7 to 2.8 percentage points, the report said.

Although the increase represents a near doubling of the risk, the result is still not considered large enough to discourage cousins from having children, said Dr. Arno Motulsky, a professor emeritus of medicine and genome sciences at the University of Washington, and the senior author of the report.

''In terms of general risks in life it's not very high,'' Dr. Motulsky said. Even at its worst, 7 percent, he said, ''93 percent of the time, nothing is going to happen.''

The report is in today's issue of The Journal of Genetic Counseling.

''As genetic advisers,'' Dr. Motulsky said, ''we give people all the various possibilities and risks and leave it up to them to make a decision. Some might decide a doubling of the risk is not something they want to face.''