In their analysis, the researchers found no evidence of gender-based parenting abilities, with the "exception of lactation," noting that very little about the gender of the parent has significance for children's psychological adjustment and social success. They found there are far more similarities than differences among children of lesbian and heterosexual parents. On average, two mothers tended to play with their children more, were less likely to use physical discipline, and were less likely to raise children with chauvinistic attitudes. Studies of gay male families are still limited.