The parents... that is what is wrong with those kids, vash. I'm sure they act like that at their house, so why not at yours, too? Bad parenting.
Actually, lazy parenting, too... for her to let them act up and mess up your place, you know?
It's normal for a 3-year old to ask a million questions.
This guy is the best no-nonsense parenting guru I know of... if you ever decide to have a kid or two, get a couple of his books, and you'll get compliments on your kids from other parents:
http://www.rosemond.com/
Follow his advice and it won't be so hard and you won't lose your sanity. Kids are great and a lot of fun if you do it right.