[SeeSac]

If your twin lived inside you, then you might have a point.

Fetus in fetu.

[Tublecane]

“Fetus in fetu”

That’s closer to the subject, but still off-base. As you know, those are not really fetuses, but rather tissue that might have grown into a fetus of its own before it was surrounded by a successful fetus. So, yes, A person can in a manner of speaking have a twin inside of them. But that twin bears no resemblance to eggs, which are the subject of this thread.