I really like this. Marilyn seems like a really well thought out and developed character. I like the background info you've given so far.
My mother always said that I was born with running shoes on my feet. But what I've always thought was that itchy feet were just genetic.
To me, those two lines stuck out the most. You can tell before you even read that she had moved around a lot and that she didn't have the typical "pouting and crying" reaction most people would have. I think it sums her up really well.