Why, you might ask yourself, and I certainly did, does she have a line from U2's 1991 hit The Fly on her for eternity? She couldn't possibly have been legal tattooing age 14 years ago. Though I suppose it makes sense: you wouldn't want to rush home on the day the single came out, and then rush back out to the inkman. Far more sensible to listen to it at age 10, roll it around in your head for a while, then at 16-18 go down, put down your cash and say "This is what I am. Complete me."
EDIT: I forgot the best bit, which is that as I was leaving the train I got a look at the tattoos she had on her forearms. One was a generic sexy lady devil, but the other was Optimus Prime, which raises a whole new set of questions, including but not limited to more frenzied age-calculations.