Newt Gingrich signed on to an anti-gay marriage pledge while campaigning Thursday in Iowa and said that people choose to be gay in the same way that others choose to be celibate.

The topic of homosexuality was first broached during an interview with The Des Moines Register editorial board in the morning. Asked if he thought that people chose to be gay, Gingrich said that he thought it was "a combination of genetics and environment."

"I think people have a significant range of choice within a genetic pattern. I don’t believe in genetic determinism, and I don’t think there is any great evidence of genetic determinism," Gingrich added. "There are propensities. Are you more likely to do this or more likely to do that? But that doesn’t mean it’s definitional."

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Gingrich was then again asked if an individual could choose to be straight.

"Look, people choose to be celibate," Gingrich said. "People choose many things in life. You know, there is a bias in favor of non-celibacy. It’s part of how the species recreates. And yet there is a substantial amount of people who choose celibacy as a religious vocation or for other reasons."

Later in the interview, Gingrich said that he would reinstate the “Don't ask, don't tell” program if he became president.

“I think that it would be a career-ending conversation,” he said. “I don’t think that in the military you would particularly want sexual behavior to be an overt issue.”

Later, the National Organization for Marriage, which had previously criticized Gingrich his multiple divorces, said that the former Speaker of the House had signed onto their anti-gay-marriage pledge.

The pledge, which has also been signed by Mitt Romney, Michele Bachmann Michele Marie BachmannEvangelicals shouldn't be defending Trump in tiff over editorial Mellman: The 'lane theory' is the wrong lane to be in White House backs Stephen Miller amid white nationalist allegations MORE, Rick Perry and Rick Santorum, says candidates will push a constitutional amendment banning same-sex marriage and form a presidential commission to investigate "reports of Americans who have been harassed or threatened" for opposing same-sex marriage.

Gingrich's moves might endear him to conservative voters in Iowa but could be dangerous in a general election. A CNN poll earlier this year found that a majority of Americans felt that gay marriage "should be recognized by the law as valid."