There are certain biological malformations at birth that can cause some confusion about sex, but there's no evidence that sex can be changed with surgery, hormones and a president who's being held hostage by an aggressive movement to confuse people. These changes were being developed in 2012 by regulatory staff, around the time that President Obama did his flip on marriage, not your elected officials. There's also no evidence that a simple, single stall or family restroom can't accommodate anyone who wants privacy, no matter how she expresses her discomfort and desire to use that assigned to a different sex.
It was regulatory bureaucrats who changed the word sex in title IX and VII to gender. This could destroy women's sports. The Courts have interpreted Title VII's prohibition against sex discrimination to mean discrimination against men because they are men and women because they are women. It was people with an agenda within government agencies that conjured up "gender identity." Gender is for grammar; sex is for biology. Don't get snowed by language.