When one such researcher, Paul Cameron, published a paper in 2006 arguing that children of gay parents were more likely to be gay themselves, the response from the academic press was virulent, to say nothing of the popular press; the Southern Poverty Law Center, for instance, equated Cameron to a Nazi.
Not all of the vitriol was hyperbolic. Cameron does not tolerate gay people. He believes that "homosexual practice is injurious to society."
The gay press, as far back as the 1980s, labeled Cameron "the most dangerous anti-gay voice in America." Though Cameron was the first to publish papers on the dangers of secondhand smoke, the scientific community has abandoned him. The American Psychological Association long since dropped him from its membership for an "ethical" violation.
Today, Cameron is the founder and chairman of the Family Research Institute, whose "overriding mission" is to publish "empirical research on issues that threaten the traditional family, particularly homosexuality."
Schumm doesn't go for that sort of research. After Cameron's 2006 paper, Schumm listened as the academic community stated certainty of two things: Cameron was an idiotic bigot; and the existing literature showed little to no societal, cultural or parental influence on sexual orientation.
Schumm began investigating the second premise. "I just want to know the truth about something," he tells AOL News. And he found it strange that parents can influence so many facets of their children's lives -- but not in any way their sexual orientation.
Lawyers for the state of Florida heard of Schumm's fledgling research and invited him in 2008 to testify in a case. The state's Department of Children and Families was attempting to uphold a ban on gay and lesbian parents adopting children. Schumm's testimony actually ended up aiding the gay parents in the trial.
He said: "Gay parents can be good foster parents," and "The decision to permit homosexuals to adopt is best made by the judiciary on a case by case basis."
Schumm tells AOL News that he agreed to testify as one of the state's witnesses only if his evidence was not "slanted" for or against gay rights.
But also in his testimony was an inkling of the robust research Schumm has just completed. His study on sexual orientation, out next month, says that gay and lesbian parents are far more likely to have children who become gay. "I'm trying to prove that it's not 100 percent genetic," Schumm tells AOL News.
His study is a meta-analysis of existing work. First, Schumm extrapolated data from 10 books on gay parenting; Cameron, for what it's worth, had only looked at three, and offered no statistical analysis in his paper. Schumm skewed his data so that only self-identified gay and lesbian children would be labeled as such.
This is important because sometimes Schumm would come across a passage of children of gay parents who said they were "adamant about not declaring their sexual orientation at all." These people would be labeled straight, even though the passage's implication was that they were gay.
Schumm concluded that children of lesbian parents identified themselves as gay 31 percent of the time; children of gay men had gay children 19 percent of the time, and children of a lesbian mother and gay father had at least one gay child 25 percent of the time.
Furthermore, when the study restricted the results so that they included only children in their 20s -- presumably after they'd been able to work out any adolescent confusion or experimentation -- 58 percent of the children of lesbians called themselves gay, and 33 percent of the children of gay men called themselves gay. (About 5 to 10 percent of the children of straight parents call themselves gay, Schumm says.)
Schumm next went macro, poring over an anthropological study of various cultures' acceptance of homosexuality. He found that when communities welcome gays and lesbians, "89 percent feature higher rates of homosexual behavior."
Finally, Schumm looked at the existing academic studies, the ones used to pillory Cameron's work. In all there are 26 such studies. Schumm ran the numbers from them and concluded that, surprisingly, 20 percent of the kids of gay parents were gay themselves. When children only 17 or older were included in the analysis, 28 percent were gay.
Abbie Goldberg is a psychology professor at Clark University, and the author of "Lesbian and Gay Parents and Their Children: Research on the Family Life Cycle," which this year won the Distinguished Book Award from the APA. She hasn't read Schumm's study, only seen the abstract. But she says, in general, that a meta-analysis of this nature relies on sample sizes that are often too small and may furthermore brim with participants whose perspective is firmly aligned with the LGBT community. In other words, they're aware of these sorts of studies and seek them out.
"The fundamental problem with this [type of meta-analysis] is such samples tend to be biased," Goldberg tells AOL News.
Schumm says he guarded against that by seeking out so many different works. And across all his data -- the 10 books he consulted, the anthropological study, the scientific articles -- he noticed how lesbians begat more lesbians. In Schumm's study, he quotes from the extant literature the stories of young women, describing how being gay was never frowned upon in their household, and so that "option" was available to them. That said, Schumm also finds evidence of gay mothers pushing their daughters, upset over a relationship with a man, to "try out women."
Schumm says it shouldn't have taken until 2010 to do the meta-analysis. Too often his colleagues impose "liberal or progressive political interpretations" on their studies, which inhibit further inquiry. "It's kind of sad," he tells AOL News.
As if expecting a political backlash himself, Schumm concludes his study with a quote from philosopher Arthur Schopenhauer. "All truth passes through three stages: First it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident."