If not, this is a harmful labor practice because you were undercutting the wages of full adult workers.
In the same way that prison labor and undocumented workers undercut pay of adult workers, so too do child laborers.
Neither are really able to report labor and safety violations, neither are able to decide not to work, and neither are paid a proper living wage. Neither are in a position to unionize. This is not a free market, and it hurts everyone in the economy. It feels more like a regression to feudalism.
I’d say if we mandated a living wage this problem would likely sort itself out.
[edit] It's a question of balance of power between employer and employee. Hiring the powerless hurts everyone, even if you personally had a good experience in retrospect. If you want to teach kids, you can do so at a non-profit instead of Philip Morris.