Dr Ben Carson is a retired neurosurgeon and potential Republican presidential candidate for 2016.
On Wednesday he claimed being gay is "absolutely" a choice, telling CNN:
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.
The broadcaster notes Dr Carson has since apologised "unreservedly" for the "divisive" comments saying he does not "pretend to know how every individual came to their sexual orientation".
However, he said the "science" on the issue remained unclear, adding: "Some of our brightest minds have looked at this debate, and up until this point there have been no definitive studies that people are born into a specific sexuality."
Experts say there is no evidence that substantiates the claim that people choose to be gay, with criminal justice professor Helen Eigenberg telling the Washington Post: "The fundamental assumption of the analogy he's using is insane. I don't know of any research that substantiates the [claim] that men go to prison and come out gay."
The NHS meanwhile advises "you don’t choose your sexuality, it chooses you".
No one knows what makes people gay, lesbian, bisexual or straight. If you’re attracted to people of the same sex, this is normal and you deserve to be with someone you love.
You can see a video of Carson's full original comments below: