(CNN) Ben Carson on CNN. Ben Carson, a retired neurosurgeon and likely 2016 Republican presidential candidate, has an interesting theory about homosexuality.

Carson argued in a Wednesday CNN interview that people who come out as gay while in prison prove many them weren't born that way.

"Absolutely," Carson said when asked whether he thought homosexuality was a choice. "Because a lot of people who go into prison, go into prison straight. And when they come out, they're gay. So did something happen while they were in there? Ask yourself that question."

Despite his opposition to gay marriage, Carson suggested he could get behind civil unions.

"Why do gay people want to get married?" he said. "Because they want to have various rights — property rights, visitation rights. Why can't any two human beings, I don't care what their sexual orientation is, why can't they have the legal right to do those things? OK, that does not require changing the definition of marriage."

Though it is still early in the presidential race, polls have consistently placed Carson, a political neophyte and conservative favorite, near the top of the pack.

Carson has not formally announced a campaign, but he launched a fundraising committee to explore a White House bid on Monday.

NOW WATCH: 11 Facts That Show How Different Russia Is From The Rest Of The World

More From Business Insider

• Tea party favorite Ben Carson has established a formal committee to explore a presidential run
  

• Conservative U.S. activists look warily at a 'squishy' Jeb Bush
  

• The 2016 money race is on