Holt asserted that "there are thousands of studies, actually ... over 10,000" that show "the homosexual family or the environment is problematic for the child." Media Matters calls the 10,000 figure "dubious," noting it would only be possible "if a new study reaching that conclusion had been released every day for the past 27 years."
Holt's "10,000 studies" figure is often cited by Focus on the Family founder James Dobson and that Holt "relied on that statistic and other data when he co-sponsored a failed bill seeking a ban on gay foster parents." Indeed, Dobson has cited the 10,000-study figure without explaining the source of his data. He made this claim in his book Marriage Under Fire: Why We Must Win This Battle (Multnomah, June 2004), in which he asserted that "[m]ore than ten thousand studies have concluded that kids do best when they are raised by loving and committed mothers and fathers" (Page 54). According to a Media Matters for America review of Marriage Under Fire, the footnote for this particular claim states that "[m]any of these studies are either presented or represented in the following," subsequently listing a number of books and articles. Dobson did not provide any evidence documenting all 10,000 studies, but titles he did cite include: Growing Up with a Single Parent: What Hurts, What Helps (Harvard University Press, October 1994), Single Mothers and Their Children: A New American Dilemma (University Press of America, March 1988), "Long-Term Effects of Parental Divorce and Parent-Child Relationships, Adjustment, and Achievement in Young Adulthood," and "Children Who Don't Live with Both Parents Face Behavioral Problems." These examples suggest that many of Dobson's purported "ten thousand studies" did not examine parenting by gay individuals or couples at all but, rather, addressed child development in a single-parent home versus a two-parent home.