Russell More has an interesting editorial here in the Salt Lake Tribune giving the religious argument against transgendered bathrooms. His main point is that he believes God has created each of us to be a certain sex, and we must learn to live gracefully within the sex God means us to be. While I think there are many problems with that as a rationale for public school policy, he does, I think, make one good observation.
This is it: the idea that many boys and girls are not interested in, nor comfortable with, traditional gender toys and roles. Perhaps if we stopped dressing all little girls in pink, and buying them dolls, fewer would think they were really meant to be boys. And if boys were allowed by their families and culture to be mostly interested in dancing and cooking, fewer would think they were meant to be girls. Of course, there are true transgendered individuals, and I do believe we must accommodate them as best we can. I was a teacher for 37 years, and see no problem with transgendered young people using bathrooms they are comfortable in. All of the ones I knew, without exception, were gentle, timid people. Impossible to see them as predators.