I've heard theories about Mary's immaculate conception. And one of them is that Mary was actually an XXY or an XY.
Now before you blast me for using th XY theory, keep in mind its very possible for a a girl to have an XY. Some girls actually turn INTO boys in their teenage years. Let me explain.
First off, the Y is just more of an instructional gene. It activates testosterone, which then starts the development of male genitalia, etc. However, if there is not enough testosterone in the moter's uterus (which happens sometimes after giving birth to another male) then the Y is basically ignored, and just keeps the child as the "default", which is a female. Child is born, has a vagina, etc. Now, when the child hits puberty, all of a sudden, a large amount of testosterone is being produced. NOW the Y chromosome activates, and the child actually starts growing a penis, and turns into a legit male.
So I've heard variations of this theory to support that Mary might have been something along these lines, which then would someho support asexual reproduction by a female to produce a male, and therefore Immaculate Conception.