For a man ought not to have his head covered, since he is the image and glory of God; but the woman is the glory of man. (1 Corinthians 11:7)
Evangelicals have no doctrine of sex. We have Biblical commands we are scrupulous to obey and Greek words we are scrupulous to defend the meaning of, but we have no theology of sex.
Actually, though, it's worse than that: we are opposed to any theology of sex.
Yes, some of us still believe the husband should be the head of his wife. Some of us also still want the father to be the head of the home and the guy preaching Sunday morning to be an actual guy. Some of us, also, still think our church's elders should be guys.
Other than those few things, though, we believe in little more than body parts. Probably women should still be the sex that gestates and men should provide food for gestating women. Also, in most Christian homes, it's likely still good for the mother not to have to put her kids in daycare—especially while she's nursing.
Beyond men having servant leader, tie-breaking authority in private Christian places and Christians having certain scruples concerning the proper use of body parts, though, we have no theology of sex. This is the reason Evangelicals have no problem with the "gay Christian" lobby as long as these "gay Christians" living with one another in "spiritual friendships" promise not to have sex with each other. If they go off the reservation and say they're going to go ahead and have sex with each other, after all, we finally find our principles and tell them it's sin. But without the improper use of body parts, there is no sin. Identity is one thing. Body parts are something else. Body parts are serious business. They're visible. They don't lie and they have to be obeyed...