Biologically, there are only two sexes which are 'given' to a person since conception. At the same time, gender is more a psychological thing.
Transgender people should be treated equally with other people. Yes, there are several complex issues which should be resolved. Such as participation in sports, access to bathrooms and locker rooms and so on. I don't imply that every person who puts on the opposite sex closing should have access to such facilities automatically. But there should be some solution.