Men cannot breast feed. In the first years, the mother is the primary parent, by biological instinct of the child alone. After that, both are parents and it depends if the mother or the father is the better parent. But you have to really hate your child (which many parents of course do) to try to force them to live against their biological instincts when they are infants.

Many women can not either. And some children simply will not. I have two boys. One would only breastfeed and never take the bottle. The other would only take a bottle and never breastfeed.