First of course, science recognizes hermaphrodites as a phenomenon, and the children born that way are usually assigned a sex based on the best guesses of the doctors as to which sex will be "better" for the child, though often it turns out that the child has serious sex identity issues (I don't use the term "gender" as it is a grammatical category).
Second, there are a number of other factors that allow the brain to process sexual identity in different ways, and modern science recognizes that, too.
However, any person who adheres to a religious faith must by necessity eschew scientism, the notion that somehow science explains everything. Human behavior in particular is varied in its expressions and irrational desires, and thank God for that. It would be a sad, shabby little world if we all liked the same things and felt the same way about everything.
If Jenner is transitioning from one sex to the other, that decision should be respected by society. I do think that as a matter of law transsexuals should not be allowed to enter public restrooms of their chosen sex unless and until their genitalia matches that of the other people using that room, because to do otherwise would invite abuse. From what I understand (which is admittedly limited - I've never had the slightest inclination to change my sex), psychiatrists and psychotherapists work with individuals to make sure that the transsexuality is real and not due to mental illness. If professionals believe the desire is real and the person starts hormone therapy, it's not my place to second guess, and certainly not my business to pass judgment on.
ἡ δὲ κἀκ τριῶν τρυπημάτων ἐργαζομένη ἐνεκάλει τῇ φύσει, δυσφορουμένη, ὅτι δὴ μὴ καὶ τοὺς τιτθοὺς αὐτῇ εὐρύτερον ἢ νῦν εἰσι τρυπώη, ὅπως καὶ ἄλλην ἐνταῦθα μίξιν ἐπιτεχνᾶσθαι δυνατὴ εἴη. – Procopius
Ummaka qinnassa nīk!
*MySmiley*