It’s not “what you were born as”, it’s “what you were assigned”. At birth, the doctor takes a quick look between your legs and picks M or F. That is not a complete diagnosis of your gender. Even the XX and XY can be expressed differently. You can have a Y, but there are other things that have to happen to activate the male, or you can have a Y but it is not activated, so you appear and feel female. I don’t know the details. All the variations are discussed in the first half-hour of this radio show: