My child will know that he was born into the correct body.
He can be feminine. He can wear whatever he likes (if it's safe and appropriate), he can dance, and sing, and play, and be whatever he would like to be - I only hope that whatever he is, he will try to be a good one.
I will not lie to my son. I will not tell him that his differences are a sickness that needs medical treatment. I will raise him with a firm foundation of truth, and I will be happy to accept whatever he becomes. I just want a healthy child.
I hope you'll still feel the same way if you later find out they're your daughter instead.
Note: not saying I hope your child is trans, I wouldn't wish that on anyone.