Parent’s sexual orientation isn’t a relevant factor in children’s development, according to a new study. An international team of researchers carried the first systematic review that looked at children with same-sex parents and found found that kids with sexual minority parents fare as well, if not better, than those of heterosexual couples, undermining the unsupported argument against equal marriage and adoption.

The number of children in families with parents who are lesbian, gay, bisexual, transgender, and queer has increased in recent years. A study estimated in 2018 that there are 114,000 same-sex couples in the US raising children. However, sexual minority parenting continues to be a controversial topic for some people around the world.

Previous studies suggested children raised by lesbian and gay parents don’t experience adverse outcomes compared with other children, even doing better in some areas. However, other studies have shown contradictory findings that children from sexual minority parents may have worse developmental outcomes, such as children’s health. So in the new study, researchers carried out a systematic review — a study of studies to see how all the data adds up.

Kids and sexual minority parents

“Contrary to many concerns, our review found most family outcomes were similar between these two family types, and sexual minority families have even better outcomes in some domains, such as child psychological adjustment and child-parent relationships,” the authors of the new study wrote in the journal BMJ Global Health.

In their study, researchers analyzed 34 studies published between 1989 and 2002 from countries where same-sex relationships are legal – including the US, the UK, and Europe. These studies compared the development of kids raised by heterosexual parents with those brought up by lesbian, gay, bisexual, queer, and transgender parents.

Children of preschool age with sexual minority parents were found to have significantly fewer psychological problems than those with heterosexual parents, although no difference was found among older kids. When looking at other metrics, such as family functioning and couple relationship satisfaction, the researchers also found no difference.

Growing up with sexual minority parents may even “confer some advantages to children,” the researchers wrote. They tend to be “more tolerant of diversity and more nurturing towards younger children” and exploring gender and sexual identity “may actually enhance children’s ability to succeed and thrive in a range of contexts,” they added.

However, they said there are also big risks associated with being a member of a sexual minority family, such as “stigma and poor social support.” They called policy-makers to work on improving family outcomes. “We need to learn more about how communities around the world can support positive development among all children of sexual minority parents,” they wrote.

Rachel Farr, an expert in sexual minority parent families at the University of Kentucky, who was not involved with the work, told the Guardian the study included controversial and even discredited research. She said the sexual orientation of parents is “far less important” to children’s development as compared to what actually happens within families.