I know I didn't do more than help take care of critters when I was a kid
that's why I never got more than a hamster, who eventually escaped
we had big critters though and as soon as I was old enough to lug a bucket, I was given the opportunity to earn money during vacations to take over the horse care - an opportunity earned by sticking to the commitment
I had to have been around ten by that time

in the case of Mikhaila - I'd never get her anything I'm not willing to take care of, and she really has never taken care of anything beyond a few enthusiastic attempts that petered out pretty soon
now she's committed to cat litter duty though and doing a decent job
if she keeps it up, she can get her first pet she'll be completely responsible for herself
so far a lion-headed bunny is at the top of the wish list