Well, I just got one thing to say, it hasn't worked for me yet so I seriously doubt just by the will of the mind it will ever work. Interesting theory though and could be possible with different energies, other than just thinking and wishing it, may be able to effect the gender developement in the womb. Or eventually be able to harness certain energies to manipulate the whole genetic structure outside the womb, but I really don't think we will ever see it in our lifetimes. But really, you can convince yourself of anything so if you wish hard enough and have enough mind power, you may actually change genders in your mind and that mind can see that gender in the mirror. But that would be considered an hallucination or a dellusion.
Cancer and other illnesses are totally different than changing genders just by positive thoughts and so on. Positive thoughts and the mind over matter type deal is very possible in that it may strengthen the immune system enough to attack and destroy the cancer cells. Yes there are stories of the body mysteriously curing itself from cancer and other serious illnesses. But I have yet to hear of someone wishing to be the opposite gender and one morning wake up thier preferred gender.
So if this theory is correct about changing genders in the same way as ridding the body of cancer, what if the immune system attacks evey cell of the body because of the YX or XX chromosomes contained in the genetic structure of those cells?