Gary Gates of the University of Southern California told The New York Times black and Hispanic gays are also more likely to have children. Gates, a demographer, analyzed data from the Census Bureau's American Community Survey.
The Census found 581,000 gay couples in the United States in 2009. About one-third of female couples and one-fifth of men were parents.
In southern cities such as Jacksonville, Fla., and San Antonio, about one-third of all gay couples are parents, Gates said.
Gates said blacks and Hispanics, living in communities where gays faced more discrimination, may be more likely to bring children from heterosexual relationships into their new lives.
"People grew up in church, so a lot of us lived in shame," said Darlene Maffett of Jacksonville, who had two children as a married woman. "What did we do? We wandered around lost. We married men, and then couldn't understand why every night we had a headache."
Bob Witeck, head of Witeck-Combs Communications, said there is another message to be learned from the numbers.
"We're starting to see that the gay community is very diverse," he said. "We're not all rich white guys."