"So, in taking a wild guess here, that being that I absorbed my feminine twin, she some how still lived on as a part of me, as I grew up. Lots of babies are merely treated by their parents as gender-neutral until they grow out of infancy. The years before puberty, both genders are almost identical... with one exception of course. It all changes after that. Or at least, it should've in my case.
"She does not have a mind of her own and yet all these pre-adult years, she's been watching and learning how to be female, just like any girl growing to be a woman. Since I didn't become effeminate from this it's probably that she kept it for herself until she finally gathered some kind of strength as she just wanted to be whole. So by this time in my life, like women being born full blown from Zeus of Greek mythology, where the women were separate beings apart from Zeus, my sister is me and I am her.