If you're one of three sisters, you may – and please don’t shoot the messenger here – be responsible for a decrease in your mother’s wellbeing.

That’s according to a study from the UK, where, Dr Mary O'Kane, Lecturer in Psychology and Education and author of Perfectly Imperfect Parenting, tells Cormac they have traditionally been more accustomed to two-child families.

Mary – herself one of three daughters – gave Cormac a summary of this report and its weirdly-specific conclusions:

"They knew that parents in the UK who have two children of the same sex are more likely to try for a third child because, they’re assuming, they’re hoping to have a child of the opposite sex. They started to examine if it made a difference, the sex of that third child and what they found was parents – particularly mothers – who’d had two boys and they had a third child and it was a boy – didn't really make much difference.

"Parents who had three children of whatever sex, didn’t really make a difference. But parents who had three girls, the mothers in particular had significantly lower wellbeing for up to 10 years after the birth of the third girl."

Getty Images

The conclusions came from two extensive studies of 17,000 people born in 1958 and a further 17,000 people born in 1970, but what do those unusual conclusions mean and what can we take from them? Mary told Cormac what the studies themselves drew from the reports:

"They were saying that perhaps mothers didn’t want too many females in the household. Then they were saying that maybe boys have traditionally superior earning power and whatever. But can I be honest with you Cormac? I am wondering if it’s pressure being put on the mums because, as I said, in the UK it would be very traditional – you know the old saying, a gentleman’s family... So, I wonder, traditionally, maybe the mothers with two girls were being put under pressure to have a boy and maybe pressure to have a son and so were more disappointed. Maybe the mothers of boys weren’t as disappointed."

Cormac is eager to stress his belief that this UK study does not apply to Irish people because, "Irish daughters obviously are far better and Irish mammies are far better." This is a sentiment that Mary’s own mother can attest to:

"I asked my mum what was it like having three girls and she assured me she was delighted with herself. It didn’t affect her wellbeing at all."

Getty Images

So many mothers in this survey having their wellbeing diminished by having three daughters is something that both Mary and Cormac find hard to get their heads around:

"I’m genuinely really shocked, Cormac, and wouldn’t have expected this. Funny, sometimes you can have a conflict in temperament, so maybe you have a child and you feel that child is just very different temperamentally to you. We talk about some children being lambs and some children being roosters, you know, some being really quiet and some being lively. And sometimes that might cause a change in the wellbeing of a parent, but gender? I’m just really surprised."

The conclusions of the report surely warrant further investigation, but unfortunately, Mary says, the people who conducted this research don’t seem to have pursued it:

"I’d love them to go back and ask the mothers if they have any idea why. I’d love them to drill into it. I’m not sure I really believe the superior earning power argument or that mums just don’t want too many females in the house."

While we’re waiting for the authors in the UK to publish a deep dive into the results of their survey, we can relax and enjoy the vibrant wellbeing of our happy mothers and daughters, right?

You can hear Cormac’s full chat with Mary on Drivetime by clicking above.