It's not unusual for kids to take classes at the local 2 yr Jr. or Tech college while still attending high school. My adopted niece did that to get some nursing courses. My stepdaughter took calculus at the local state university while still in high school.

The distinction here is that if you asked either of my girls about it they'd say "I took a few classes"... not "I started college at 16". She's getting away with this because her fanbase is too oblivious to call bullshit.