STROKE the belly of a newborn female rat for a few hours a day and chemical “caps” will appear on its DNA that make its brain look more like that of a male.
This extraordinary finding suggests that some biological differences between male and female brains may not be decided during fetal development, but instead appear after they are born.
According to traditional thinking, sex-specific differences in mammals are determined in the womb by genes on the X and Y chromosomes, with the prenatal hormones the fetus is exposed to also playing a role.
Recently, however, it has become clear…
