I feel as though wanting to change your gender and feeling like you were born in your own body can definitely be a rational thought, when societal pressure and norms are applied. Considering how differently men and women (in general) act from each other, and how their lifestyles and stereotypes differ, someone may feel as though they fit in with the other sex. I think however, trying to alter your body to achieve this is a potentially harmful way to go about this, with hormone imbalances and such (don't quote me on this, I'm just guessing here). Being a hyperfeminine man or hyperma… Read moresculine woman is a lot less medical, but people have the right to choose what they do with their bodies, so ultimately it doesn't matter. You might think someone is crazy for undergoing a surgery like removing ribs or a cosmetic surgery of similar risk, but we don't throw them in insane asylums.
Now, a person not being able to change their gender- that really depends on whether people are considering gender as your sex, so man or woman, female or male, or if you consider gender a social construct. You can't change your biological sex, but I mean, there are things you can do medically to look or feel more like your desired sex. And gender, well, again that depends on how you view it. If you view gender as man or woman like sex, then the above applies. But if you view it as whatever you want to be then I guess identify with whatever you want?
Again, I really am not well researched in all of this, but these are just some thoughts I had.