with Karen Ehman My friend Sheila Wray Gregoire asked a great question last week: “When Does Childhood End?” I agree with her premise that one of my duties, as a mom, is to help my kids find their route to independence, maturity, and purpose. So it’s been hard to admit that I was a “smother mother” when my daughter was in high school. I ran interference with my daughter’s teachers so often, she did not learn how to advocate for herself. She didn’t know how to ask, “When can I come make up the quiz I missed yesterday?” or “Why did …