And they found they did better than kids growing up with a mum and a dad.
It was the largest and longest ever study of same-sex parents. The lesbian mums in the US survey signed up around 20 years ago, before one of them got pregnant by a sperm donor.
Their children were then tested and interviewed as they grew up. And they were compared with a similar group of kids being raised in conventional mum-and-dad families.
Their development turned out to be the same as the kids brought up by heterosexual parents. Except that by the time the two-mum kids were 17, they had fewer social problems and were less rebellious than the kids with dads. What’s more, they got higher grades at school. In fact they were better at most things.
The researchers think the lesbian mothers did so well at parenting because they both tended to be involved and committed right from the start.
And compared to heterosexual fathers, they were less domineering, and they didn’t hit their kids. This may well be why the teenagers were more chilled out and had less trouble with authority.