I just bet their parents forced them to preach

Child abuse, yeah that makes sense. Can't you just see the parents with the wooden spoon telling their kids, "Preach or we'll beat you black and blue and withhold dinner, too."

BTW, I'm not advocating kiddie preachers -- I believe that those who teach should be trained. I don't think Paul had them in mind when he said this:

1 Timothy 4:12 Let no one despise you for your youth, but set the believers an example in speech, in conduct, in love, in faith, in purity.