Physiologically speaking, Brooke Greenberg is an infant with the mind of toddler. Only thing is that she turned 16 just this January. It’s hard to estimate the parents opinion, especially as I wasn’t able to find almost any constructive data.
http://www.zmescience.com/girl-that-doesnt-age-baffles-scientists-a-16-year-old-is-an-infan
