How fatherhood changes the brain
A host of studies found that a man’s brain goes through significant changes when his child is born. In the first few weeks after birth, the father’s testosterone and cortisol decrease and there are increases in estrogen, prolactin, oxytocin and glucocorticoids. All these changes promote bonding, empathy and altruism.
https://bigthink.com/mind-brain/neuroscience-of-fatherhood?rebelltitem=1#rebelltitem1