(CNN) - GOP presidential frontrunner Newt Gingrich on Thursday said he believes homosexuality stems from a "combination of genetics and environment."
"I don't believe in genetic determinism, and I don't believe there's any great evidence of genetic determinism," Gingrich said before The Des Moines Register's editorial board. "There are propensities. Are you more likely to do this, or are you more likely to do that? But that doesn't mean it's definitional."
Calling himself a "traditional, classic conservative," Gingrich said he believed marriage should be between a man and a woman and insisted he would not have repealed the controversial "Don't Ask, Don't Tell" policy in the military.
But the former House speaker was careful to draw the distinction that he believes homosexuality is both genetic and a lifestyle, stopping short of agreeing with some who believe it is entirely a choice.
"I believe it's a combination of genetics and environment," Gingrich said. "I think both are involved, and I think people have many ranges of choices."
Asked if he thought a person could choose to be straight or gay, Gingrich again said, "People have many choices within a genetic pattern. It is not a pre-determined, either or."
He also pointedly noted an acceptance of homosexuality, saying he doesn't believe people should be mistreated based on their personal lives.
"I'm against discrimination of people based on their private behavior," Gingrich said.