There is a really dangerous precedent here. Don't like the gender of your child? Just change it.
How many poor fucked up adults are there going to be because mummy wanted a girl so had his penis cut off.
Although I get the fact that it is easier to transition before puberty, we would never allow a child to make a medical decision for themselves and that age and a parent should never be allowed to push this without the full and informed consent of the child.