As the authors mentioned, ~30 years is the age many people have kids, and it is already well known that female brain changes after giving birth, for example. The authors didn't research if being a parent can explain a part of the difference (and also if parent brains are any different than childless people brains).
I'm personally curious about this: I'm slightly above 30, I observed significant changes in my behavior recently... and I became a parent this year.
I'm personally curious about this: I'm slightly above 30, I observed significant changes in my behavior recently... and I became a parent this year.