| But their argument is far from consensus: in Forbidden Relatives: The American Myth of Cousin Marriage,
Kansas State University anthropologist Martin Ottenheimer argues that
the bans were driven by now-discredited 19th century research on birth
defects among children born to first cousins.
Whatever their
motivations, the laws are not supported by science. According to the
National Society of Genetic Counselors, birth defects are 2 to 3
percent more common in children born to first cousins than among the
general population — a real risk, but not enough to justify the bans.
"It's a form of discrimination that nobody
talks about. People worry about not getting health insurance — but
saying that someone shouldn't marry based on how they're related, when
there's no known harm, to me is a form of discrimination," said Robin
Bennett, a University of Washington genetic counselor who led the NSGC
study.
Precise statistics on cousin union frequency in the
United States are hard to come by, she said, but discrimination and
ignorance have serious consequences.
"I'm aware of people who
have been afraid to tell people that they're in love with their
cousins, who've become pregnant and potentially terminated a pregnancy
based on false information," said Bennett. "Or they didn't marry the
person they loved because of their concerns."
"The laws against cousin marriage are archaic, outdated, and counterproductive," said Ottenheimer.
Repealing these laws doesn't seem likely in the near future:
gay marriage remains a more pressing issue. But anyone who
wants to fight for cousin marriage won't have to fight against science.
"Ultimately it's a political question about what you allow
individuals to do, and what that says about the structure of society,"
said Spencer. Citation: "'It’s Ok, We’re Not Cousins by
Blood': The Cousin Marriage Controversy in Historical Perspective." By
Diane B. Paul and Hamish G. Spencer. Public Library of Science Biology: Vol. 6 Issue 12, Dec. 22, 2008.Images; 1. Emma Darwin / Darwin Day Celebration
2. Charles Darwin / WikiMedia Commons (Charles married Emma, his first
cousin, shortly after returning from his expedition aboard the Beagle)
3. Map of U.S. cousin marriage bans / PLoS Biology
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