The findings, published online this week by the Proceedings of the National Academy of Sciences, provide the strongest evidence to date in support of the notion that
sex chromosomes acting on single cells play a role in differences between male and female brains.
This is why two brothers in the same family can look and
act totally different from one another even though they come from the same parents — it all depends on which genes (
chromosomes) were randomly chosen when producing the
sex cells of the mother and father.