of children who are fairly persistent in their cross-gender play, but are prepubertal, only about 20% on to be transgender. 80% will not be. what i would say to parents is that if your child is getting close to puberty, or worse, is already in and is showing this kind of behavior, particularly underwear wearing binding breasts, etc., then you need to get help for that child fast. that may be calling your previous attrition -- pediatrician and asking for a gender specialist to meet with your child, because a child who holds on to the belief that they are in the wrong body at the onset of puberty feels like pinocchio becoming a donkey. they may well take their life. these are the kids who are the real deal. charlie: over the series, eric you and i found a range of things that we traced to the brain and understood that some levels and cases -- what we understood about what was taking place within the brain was large , and in some cases small. where do you put this in terms of understanding what is going on here i go eric: we are at the early stages of understanding what is going on. this