Has anyone else noticed this "regression" among the three boys? In the early season they were kind of tough. They made their sisters cry several times. Even Mike made Carol cry once.

But later on, suddenly they are peace and love, flower power kids. The changes were almost out of character. Peter's change seemed the most drastic.

I've noticed that too. I think that the boys were more insensitive to the girls at first because they saw them as outsiders and were not used to having girls around. In the later seasons after they had all lived together for a few years and had all grown closer the boys really saw the girls as their sisters and not outsiders.