Incest is for hicks. That's the stereotype among educated liberals: Homosexuality is urbane, polygamy is for Mormons, and incest is for hayseeds. So when David Epstein, a Columbia University political scientist, was charged last week with third-degree incest for allegedly shagging his adult daughter, the blogosphere erupted. Conservatives called it another sign of moral chaos. Liberals said it was gross but shouldn't be prosecuted. One side defends the privacy of all consensual sex; the other side sees an inexorable descent from homosexuality to incest.
Let's try to come up with something better. If gay sex is OK, how can incest be wrong?
The old answer was genetics. Germany's high court relied on that argument two years ago when it upheld the conviction of Patrick Stuebing for sex with his sister. Of the four children the couple produced, three had physical or mental disabilities. In general, studies show a significantly higher rate of birth defects in offspring of incestuous couples. The reason is simple: Every family has genetic flaws, and if you reproduce within your family, you're more likely to get two copies of the flaw—thereby producing the defective trait—instead of acquiring a new, protective allele from another family.
Many incest laws in the United States invoke this concept. In patently eugenic language, they forbid sex between "consanguineous" (blood-related) partners. But this rationale won't withstand close scrutiny or the march of technology. If genetics is the issue, just get a vasectomy. Then you can bang your sister all you want. Or skip the vasectomy and bang your brother. Gay sex can't make a baby, so the problem is solved. As the German court noted, Stuebing could have dodged Germany's incest law in precisely this way.
Epstein has been charged under a different law. It prohibits sex with any close relative, "whether through marriage or not." It also applies not just to "sexual intercourse" but also to "oral sexual conduct or anal sexual conduct." If the law were rationally based on genetics, it would ignore sex acts that can't make babies, and it would distinguish relatives by blood from relatives by marriage.
What about the Scottish woman who was sentenced to probation—and remains under threat of further prosecution—for sex with her half-brother? She was sterilized years ago. You can't prosecute her based on a risk of birth defects.
So let's set aside genetics and consider the next question: exploitation. Nowadays, when we talk about incest, we tend to think of child sexual abuse. That's how we use the term in the repressed-memory debate and in abortion legislation. When politicians such as President Obama make exceptions in abortion laws for "rape and incest," they're using the terms synonymously, except that in the incest scenario, the rapist is your dad.
But you can't prosecute Epstein under that theory. According to news reports, his daughter is 24, and their affair began in 2006. That makes her an adult. Furthermore, police say the sex appears to have been consensual. Four years ago, Ohio's Supreme Court upheld the incest conviction of Paul Lowe, a former sheriff's deputy, for what the court called "consensual sex with his 22-year-old stepdaughter." And last month, a 27-year-old Florida woman was sentenced to five years of probation for sex with her father. Clearly, we're prosecuting people for incest regardless of age or consent.
At this point, liberals tend to throw up their hands. If both parties are consenting adults and the genetic rationale is bogus, why should the law get involved? Incest may seem icky, but that's what people said about homosexuality, too. It's all private conduct. To which conservatives reply: We told you so. We warned you that if laws against homosexuality were struck down, laws against polygamy and incest would follow. And now you're proving us right.
The conservative view is that all sexual deviance—homosexuality, polyamory, adultery, bestiality, incest—violates the natural order. Families depend on moral structure: Mom, Dad, kids. When you confound that structure—when Dad sleeps with a man, Dad sleeps with another woman, or Mom sleeps with Grandpa—the family falls apart. Kids need clear roles and relationships. Without this, they get disoriented. Mess with the family, and you mess up the kids.