Studies challenge widely held assumptions about same-sex parenting

But she also is bothered that some would use differences to bar same-sex couples from having kids without understanding what causes those differences.

"I hope people will take it on and look at related and more complex statistical questions," said Eggebeen. If Regnerus' findings don't hold up, why? I would see this as the beginning. The provocative findings get us to look at this."

Researchers on both sides say more research is needed and it could be years before the impact of changing family structure on children is clear.

It's an important public conversation, said Wilcox. "I think as a society we do value the well-being of children across the spectrum. We would like to create a context where kids could thrive."

If the findings are replicated, the whys need to be answered, he said. "How much instability, how much community stigma, how much biological ties, and how much differential access to the legal institution of marriage account for the differences the Regnerus study finds? I think if you look back historically on the impact of divorce on children, there were a number of chapters and a changing story emerged about the impact on children. I think the Regnerus study is bringing us to a new chapter. The first suggested no difference, the second will suggest there are some. The third chapter is going to be trying to figure out the differences."

Douglas W. Allen, the Burnaby Mountain Professor of Economics at Simon Fraser University in Burnaby, British Columbia, said that no matter what future studies say about same-sex families, scientific methods have to be protected so they can't be hijacked by political pressures on either side. Science must be robust and careful, a proper probability sample the basis for any claim about a broad population.

His criticism of most of the studies since 2005 mirrors Marks'. All but one was a convenience study, called that because the subjects are "convenient" to gather into the sample. You want to study lesbians, so you ask a friend you know who is lesbian if she'll answer questions. That turns to the snowball study, when you ask if she knows other lesbians you can talk to as well, he said.

Those types of studies made up most research on same-sex parenting. "That's totally fine to do if you're just interested in exploratory work," said Allen, who doesn't know Regnerus or Marks. "Often an area of research starts this way. The problem comes when you try to extrapolate what you find to the broader population. You cannot. It says absolutely nothing about the population of lesbian and gay parents, only about those particular ones."

Allen expects a lot of people to try to poke holes in Regnerus' work. But expected criticism that it was privately funded or not rigorous enough will be the "pot calling the kettle black. Other studies are off-the-charts biased bad," he said. Every researcher has biases, but when enough tackle a question, truth "sifts to the top."

However, it may take a couple of decades, he warned.

Disputes abound

Not everyone agrees with his assessment. "The research up to this point has shown absolutely no difference of any note — and in some cases, differences that might be considered in favor of lesbian parents," said David Brodzinsky, professor emeritus of clinical psychology at Rutgers and research director of the Evan B. Donaldson Adoption Institute. He had not seen the new studies, which the reporter did not share because of an embargo. Instead, he spoke in general terms. "In 25 years of study, more than 50 studies have not found the negative outcomes that critics are concerned about. That doesn't mean all the studies are well designed. Some are not. But there are studies that are relatively reasonable sizes, nonconvenience samples and at least reasonably representative that have been used as a database for looking at questions about same-sex parenting."

Both sides told the Deseret News they believe opposing researchers approach topics from what Brodzinsky called "a political perspective."