Because Vision is not a human, of course the Vision and Wanda couples cannot have children, but not in the normal way.
Abnormal, of course you can, moreover we discuss the Marvel comic world which is full of magic.
Using her own abilities, she created children from himself and Vision. Not only one, but two twins!
His two children will also become superheroes, namely Speed and Wiccan. Even so, they are not the original twin sons of Vision and Wanda
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