When men father children and then split their brains don’t change one bit. They are also pretty despicable human beings but that’s obvious. However, when they stick around and help raise the kids, fathers go through a period of neurognesis. Basically, they grow new brain cells and make new neurological connections specifically designed to connect to the baby. Perhaps that’s the chemical basis for the father-child bond? See The Brains of Our Fathers: Does Parenting Rewire Dads? in Scientific American. The catch to this biological change, though, is physical contact. You have to be immersed in the daily task of raising the kid. Every active father knows this deep inside. Every father knows they change — sometimes radically — when going through this, but I suppose now there is some research documenting the process. But the larger issue is even more powerful: this is more evidence that the brain keeps changing throughout life as needs arise, so if you change you can change your brain — and presumably many of the things your brain manages as well. Dive in. Change is good.