Just after beginning to explore his presidential campaign possibilities, potential GOP candidate Ben Carson found himself in hot water when he said he believes homosexuality is a choice, and that this can be proven by looking at prisons. “Because a lot of people who go into prison go into prison straight – and when they come out they’re gay.”

Christopher Hensley, criminal justice professor at University of Tennessee at Chattanooga, recently authored a study that is one of the first to examine shifts in sexual orientation while in prison. The researchers questioned 142 prisoners about their sexual orientation and found that 24 of those men changed their orientation while incarcerated. However, he says that a change in sexual behavior does not necessarily mean a change in sexual orientation.

According to Hensley, sexual habits can change in prison for a number of reasons, including lack of access to the opposite sex, or as perpetrator or victim of abuse. He also said that prison sex culture is not the same as the sex culture outside of prison, saying that Carson is “taking a simplistic view of sexuality.”

Carson, who is a neurosurgeon, made the comments to CNN when asked where he stands on gay marriage. Carson said that he does not believe that allowing gays to marry requires redefining marriage, saying that gay people want to get married because they want various rights, such as visitation or property. He says regardless of sexual orientation they should have a legal right to do those things.

Critics, such as Fred Sainz, Human Rights Campaign’s Vice President of Communications, say that Carson’s comments reveal him as “utterly unfit for office,” going on to say that Carson is putting his ambitions ahead of medical science when he suggests that people can change their sexual orientation. He says that as a doctor he would certainly know that countless medical and mental health organizations have condemned the idea that a person’s sexual orientation can be changed.

The presidential hopeful’s views have led to outrage before. In a 2013 Fox News interview Carson suggested that legalizing gay marriage would be a path toward legal pedophilia and bestiality. He apologized later for the remark, saying it was taken out of context and misunderstood.

Politifact asked numerous experts who study sexuality and criminal justice, and none agreed with Carson’s assessment. Northwestern University psychology professor J. Michael Bailey studies sexual orientation, and said that there is absolutely no evidence supporting Carson’s allegation, and “there is good evidence against it.”