I agree with 2darncute about the bio-parents. They should be listed as the childs bio-parents and a fact added to the same-sex partner as adopting the child or being the gardian. Myself being bi and TG agree that the whole gender and sex question is a challenge.
I noticed today that there is no event available for selection on ancestry.com for change of gender or for a sex-reasignent surgery.
Which keep in mind that gender and sex do not have the same menaing. Sex refers only to ones reproductive organs, where as gender has to do with who you are as a person in your mind.