I haven't had this particular problem at GameStop, being over 30, but I have had other problems.
I have, on occasion, had pushy and annoying employees there (at one particular location, locally, but not the other two) that tried to talk me out of purchases because they didn't like the genre those purchases were in or the platform they were on.
I will no longer buy from that location. If they don't want my money, I'll spend it elsewhere.
OP: As far as I'm concerned, if I make a decision about what my (currently hypothetical) child will watch or play, I don't want some idiot behind a counter second guessing me. Informing me? Sure. Trying to talk me out of a purchase? No. Provide me with the info, and then shut up.