There were never two parents raising the same child anywhere who ever agreed entirely about how to do it. When adults care about the same child, a certain amount of “gatekeeping” is bound to happen, in which each adult thinks he or she knows best about how to parent.
Here’s an example: Adam says, “Eve, you should make that boy behave.” Eve says, “Adam, he’s doing the best he can. Quit riding him all the time.” Years down the road, Cain slays Abel, and the finger-pointing commences. “I told you we were doing it wrong!”