Why?

Macey is growing up way too fast! Lately, when I ask her to do something, or tell her not to do something, she asks "Why?" Today, I told her not to touch Daddy's pants that were hanging up, she asked "why?" I gave her a reason, to that she responded "why?" The cycle continued until I kissed her. I thought the whole "why" thing wasn't supposed to start for a few years. That's what happens when an 18 month old has big sisters I guess...