[quote=@Host]
<Snipped quote by Threads of Fate>

Huh? Why?
[/quote]

Because Father and Mother aren't the same on a physical basis. Our elder siblings came about from Father altering Mother's physiology temporarily in order for them to match. With us, he didn't do that. His new body isn't the same as Mother's body, but we were able to be made regardless. That's why nobody knows anything about our biological baseline.