A new study has found that children raised by straight and same-sex parents are unaffected by their parents’ sexual orientation. The New England Journal of Medicine published the findings on Wednesday which showed that children of lesbian couples who used sperm donation were not more likely to have physical or emotional problems when compared to children of straight couples.

The subjects were matched on sex, class, gender and ethnic background. Findings determined that the now adult children raised by same-sex parents were doing as well as children raised by straight parents.

It was the largest, longest-running research investigating the development of children in “planned lesbian families,” beginning in 1986 and including 84 families led by lesbian couples or single lesbian mothers. “We were just coming out of a time period when homosexuality was considered a mental disorder,” said lead researcher Dr Nanette Gartrell. “There were people arguing that homosexual parents could not be good parents.”

While there are no long-term studies of children raised by gay male couples as they have only started building families in recent years, according to Gartrell, current studies have reported gay fathers are doing just as well.

The findings of the research were released in parts. The first, published in 2010, showing the children at age 17, said that kids of lesbian mothers had fewer behavioural problems than average teenagers. The most recent indicated the children, now aged 25, scored similarly on measures of depression, anxiety and other mental health issues to the children of straight parents.

Ryan Light, a sociologist at the University of Oregon, said the study corresponded with the “overwhelming scientific consensus that children of LGBTQ families experience no differences relative to children raised in heterosexual families on outcomes related to mental and emotional well-being and education, among others.”

In the landmark ruling that legalised same-sex marriage in the US in 2015, Justice Kennedy said that if children of same-sex couples suffered psychologically it was because of their parents unequal status. Gay adoption in the US is still a controversial issue. Some Republicans are attempting to pass a federal bill that would prohibit LGBT+ families from adopting. Ten states allow state-licensed child welfare agencies to refuse same-sex couples, however, a judge in Philadelphia recently ruled that religious adoption agencies can’t exclude gay parents.