studies which recruited samples of children in same-sex unions showed that 79.3 percent (range: 75–83) of comparisons were favorable to children with same-sex parents. In comparison, there were no favorable comparisons (0%, range 0–0) in studies that used random sampling. The evidence suggested strong bias resulting in false positive outcomes for parent-reported measures in recruited samples of same-sex parents.

According to the 2010 census data, there were 594,000 same-sex couple households in the United States- about 1% of all households. Of those couples, 115,000 reported having children. That’s only 0.02% of households in the US where same-sex couples are raising children. Finding a population that small at random is not only cumbersome but also takes considerable time which was in short supply in the run-up to redefine marriage.