Dec. 15, 2010— -- Columbia University professor David Epstein was charged last week with incest, accused of carrying on a three-year affair with his adult daughter.
According to the Columbia Spectator, the affair was consensual, but the political science teacher has been arraigned on one count of third-degree incest and could face up to four years in jail.
Epstein's lawyer, Matthew Galluzzo, said that charges against his client were still "only allegations" that have not been proven.
"Academically, we are obviously all morally opposed to incest and rightfully so," he told ABCNews.com. "At the same time, there is an argument to be made in the Swiss case to let go what goes on privately in bedrooms."
"It's OK for homosexuals to do whatever they want in their own home," he said. "How is this so different? We have to figure out why some behavior is tolerated and some is not."
But he questioned why, if the alleged incest was consensual, why Epstein's daughter had been treated by prosecutors as "somehow a victim here, when she can be best described as an accomplice."
Incest is still socially and legally taboo in the United States, but attitudes may be changing in other parts of the world, at least when it involves adults and not minors.
Switzerland has proposed decriminalizing consensual sexual relationships between first-degree relatives, like siblings and also between parents and their adult children. Any coercive sex or incest with a minor would still be illegal.
Social conservatives in that country have called the bill "completely repugnant," and a survey has shown that 60 percent of the public opposes changing the law.
American psychologists and legal experts say that there are still sound reasons why incest should be illegal, even if it appears it is a choice between consenting adults.
"It is still a social taboo and the ick factor is much stronger than the criminal factor," said Professor Joanna L. Grossman, a professor of family law at Hofstra University in New York.
"I think these relationships are inherently coercive for the same reason that professors are not allowed to sleep with students in their classes," she said.
Consensual incest is legal in China, France, Israel, the Ivory Coast, the Netherlands, Russia, Spain and Turkey, according to a 2007 report from the Max Planck Institute in Germany.
The report was commissioned after a pair of siblings who had grown up separately but later reunited and had children.
Patrick S. was raised in an adoptive family and his younger sister Susan K. remained with their mother after a divorce. The pair met again in 2000 when he was 23 and she was 16 and moved back in with their mother. They subsequently fell in love and had four children.
Welfare authorities removed the three oldest children from their parents and Patrick was convicted of incest and was imprisoned for two and half years.