I think common app uses turnitin.com don’t they? I thought this was a new thing this year? Maybe I’m wrong, but I thought I read that somewhere.
Nevertheless, it’s his business, not yours. Too bad that kids are so stressed out about getting into HYPS that they 1) think someone else’s essay can get them admitted and 2) can’t even write an essay in their original voice, which is what adcoms want anyway. Sad.