Puberty is the third surge of sex hormones. The first is prenatal, and the second - called "minipuberty" - typically occurs before six months in boys and bef

Puberty is the third surge of sex hormones. The first is prenatal, and the second - called "minipuberty" - typically occurs before six months in boys and before two years in girls. Some discussion in this paper: https://www.karger.com/Article/FullText/508329 https://www.karger.com/Article/FullText/508329 (and, yes, it's skeptical that hormones significantly influence behavioral differences between boys and girls - but it's clear that boys and girls have gone through different hormonal trajectories even early in life).