It is not a myth to have a woman or mans reproductive parts and identify as the opposite sex. Whether you believe in the fact that people can be born with one gender and identify with another or not, it is happening so it is not a myth.
Transgender : denoting or relating to a person whose sense of personal identity and gender does not correspond with their birth sex.
He knows that his body will always be one that was born female, but he identifies as male. I can not imagine being in a body that I do not feel is mine. This is not something new, just has been in the news the last few years. I do not think anyone believes they can change their chromosomes, but they do what they can to live a life they feel comfortable with, and just want to be allowed to live as they want. If you are a male or female it does not change my interaction with you. I do not care what you identify with, male or female.