I think alot of behaviors are passed down the generations, children live what they learn but it doesn't always take in every sibling. I'm a neat freak, as my mother before me and her father before her. However, my brother is a slob.
My mother is the only one of her siblings like that. Could be because she identified more with her father, the neat freak, more so than her mother who really didn't care about the mess.
Anyway, neatness seems to run in my family, but it stops with my kids because although they are closer to me, their father is a powerful influence type of authority figure and he is a slob, so they tend to take after him a bit although not as bad as he is!
Hey, what's wrong with being clean anyway? At least they won't have to bring in firemen with axes to plow through your house in an emergency like you see on T.V when packratting gets the best of some people!