I think it depends on the age of the kid and if he has income he can afford to lose.
I first started betting at 16 but my mother had to call my bets in to her bookie b/c he would not take a minor as a customer. She knew how much my check was every 2 weeks and would not call in any more bets once i lost a certain amount.
When i turned 18 i got my own bookie and didnt have moma to cut me off hno:
First off, I'd be shocked. She is 8 yrs old. Secondly, (if she was old enough) I would say "Does this look like the face of an antiLoser? Who ya taking?"