Some expert information might be helpful - or at least Wikipedia.
Several attempts by me to give links or quotes have been labelled spam by the forum security program. Hm. Just google 'gender identity'; there is a basic article on that and gender confusion at a site called healthychildren dot org, and a pile of the usual at Wikipedia under the same phrase.
Again, I suggest using a URL shortener like bit.ly with recalcitrant URLs. I don't know that it's foolproof but it has worked for me in the past.