Gender Identity Disorder in 4 yr old

Here is a story of a 4yr old (now 5) that was born a boy and now identifies as a girl.  He has the full support of his family and his primary school. 

Here is my favorite line from the mom:

She admitted: "I would love to have my son back, but I want him to be happy. If this is the route he wants to take - if this is what makes him happy - then so be it. I would rather him have my full support.

It's a good story and I hope you read ALL of it, because I know your next (or at least one of your next) questions.  What happens when he gets older.  Here is her answer:

"When he gets a bit older, to Key Stage 2, then obviously the law changes and there will be more difficulties surrounding the bathroom issue, but we'll cross that bridge when we come to it - it may be that Zach will use the staff toilets.

You might think the parents as naive or ignorant, but in this case (as in many) I think the parents are the ones best to make a decision.  Comment either way.  I would like to hear your thoughts.

-Candi