While there has been a lot of research about how motherhood affects women, Dr. Rilling has been working to fill the gap by researching the effects of fatherhood on men. In the article he explains the effects of testosterone on the behavior of avian, primate, and human fathers, as well as his research on the effect of fatherhood on testosterone levels in men.

https://aeon.co/essays/how-raising-children-can-change-a-fathers-brain