Maturity

This has been on my mind for awhile, but was really hammered home with the kids' visits. When are we "mature"?
I'm going to be 48 this year, and Dear Old Sarge will be 50 soon. I honestly don't feel that old, and I'm VERY sure I don't act it. But how exactly does someone that age act? Does being mature include a preoccupation with money and possessions? I notice that people with more money and toys than I have seem to be concerned with keeping and having more money or toys. It must involve alot of responsibilty and worry to do that all the time. I just don't have the mental wiring needed to be that focused on material things.
Sometimes I don't know if I'm fun for my age, or ridiculous.
Case in point- we still have farting contests. I laugh until I almost wet myself.
Is that just a nice, warm family activity or the sign of someone who can't grow up?

I'm not sure where I'm trying to go with this- just looking at where I'm at and wondering if it's where I should be.