It's as Lolita mentioned, the respect of the bond mother and child experience during the incubation period of the child is the key.
In fact throughout nature you tend to see the mother with the cubs while the father is off in some corner. Some husbands view having a children as a demotion for themselves in their own household. :)
Having said that in many cultures a female's virginity is valued much higher than a male's virginity. The female body has been worshiped and admired throughout the history of mankind.
This of course has lead to many "double standards".
It's especially true in matters of their sexual behavior and parenting.
A mother going through a divorce who elects to have the children stay with (their father) is often frowned upon by many in society.
On the other hand a man who steps up to the plate to feed, dress, and read to his children is practically given a medal of honor!