The Netherlands was the first country worldwide to legalize same-sex marriage, done in 2001. The economists used government data to track all children born in the Netherlands between 1995 and 2005.
Research done by economists Deni Mazrekaj, Kristof de Witte, and Sofie Cabus of Belgian University KU Leuven found that children raised by same-sex parents had higher tests scores in elementary and secondary school. They were also more likely to graduate from high school.
“The results indicate that children from same-sex couples outperform children from different-sex couples on standardized test scores at the end of primary education by 0.18 standard deviations,” the researchers wrote. “Our results suggest that children from same-sex couples are 6.7 percent more likely to graduate than children from different-sex couples.”
Whereas prior research on children of gay and lesbian parents often had a small sample size, this study followed all children in the country born between 1995 and 2005 through primary school and beyond. 1,200 children raised by same-sex couples and more than 1 million by different-sex couples were tracked.
Likely to be the reason for the difference in performance, researchers found, was that same-sex parents were on average wealthier, older, and more educated than their heterosexual counterparts. Because same-sex parents often use expensive fertility treatments, they’re very motivated to have children and tend to be considerably wealthy.
“It is difficult for same-sex couples to obtain children, so they have to have a high socioeconomic status,” said Mazrekaj. “Research shows that socioeconomic status positively influences the school outcome of children.”
When income and wealth were controlled, the gap between the groups shrank, but children of same-sex parents still had slightly higher scores.
This research controlled the effect of divorce that some children of same-sex couples may experience.
“Many children come into a same-sex family through divorce of a homosexual parent with a heterosexual partner and therefore did not grow up in a same-sex family,” the economists wrote. “Divorce may exert an independent negative effect on school outcomes.”
When this was controlled and only children born to and raised by same-sex couples were looked at by the researchers, they saw higher education performance compared to kids with heterosexual parents.