You most certainly can (and should) expect people (men and women) who have kids to change their behaviour. They're meant to have grown up and become responsible, not continue to get drunk in bars, but now with a child in tow.
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snipped wall of text]
No, people do not suddenly “change their behaviour” and “become responsible” when they have children.
Um, yes they frequently do just that. Most of my peer group and I acted irresponsibly before having children. After having children, we realised we needed to act responsibly, so we did so. And we continue to do so. As do millions of others.
(n.b. using walls of text does not validate a flawed argument).
I don't have children myself.. yet, but my sister was a party animal until she met her husband and settled down for children and took the responsibility however there are woman who don't and that will have a dramatic affect on their kids.