Well, we all know that under aged gambling is bad, and for such winnings to come, the parent(s) is/are aware of such activities been going on for a certain period of time before an outcome of a big win, of which was also communicated to the parents.

There's a saying, train up a child in the way they should grow, and when they are old, they will not depart from it. If this principle sticks with such a family, then the parents are either in the gambling system, or they approved such acts.

For me, I am not a gambler, but for a big win as you said, I will let use of my ID, otherwise, the child can look for someone else to make bargains with at the end of the day.