I remember this girl on the local news, written in 2004.
Fourteen-year old Alia Sabur, a Long Island, N.Y., native, has enrolled at Drexel to pursue a doctoral degree in mechanical and electrical engineering. She is the youngest Ph.D. student in the United States. A summa cum laude graduate of Stony Brook University with a bachelor of science degree in applied mathematics, Alia will study and research nanophotonics, which she describes as �the study and creation of electronic devices using optics at the nanoscale.� Alia is expected to receive her degree in 2007.
She actually got it in 2008, aged 19. Young, but not mid-teens. I don't dismiss that someone might have got a PhD aged 13-15, but I'd expect it to be really unusual even among the vvv PG. There's really something that's a lot more to do with emotional and social maturity than scientific intellect that's important for sustained research. (And besides, once you get to doing a PhD, why rush it? By that point you probably realise it's one of the best chances you're going to get to go into something in depth without having to worry too much about your paper publication rate :-)