The House Always Wins
Of all the things you probably don’t want your child to learn from your nanny, blackjack is probably somewhere at the top of the list. Kids shouldn’t gamble because it’s immoral, it’s addictive, and they don’t have money. It’s only after they start making money on their own that they can squander it at the blackjack table.
This nanny, for whatever reason, decided that it was high time for this underage child to learn how to play cards. She must’ve been a pretty good teacher, too, because according to the OP’s aunt, their cousin was up $50. The house—or in this case, the homeowner’s child—always wins.