Andrew Huberman· PhD
If you think about it, it's kind of strange that just the mere act of being a parent or parenting can change testosterone levels so dramatically or estradiol levels so dramatically, what is it? Is it the sweat of the baby? Is it their saliva? Is it the sight of the baby? Is it holding the baby, or is it all those things? It turns out that many of those effects are because of smell, or in some cases, even possibly pheromones.