User blog comment:Xilinoc/Ch. 546 - THE LAST 9DAYS/@comment-4317207-20130718030758/@comment-11051098-20130718184532

In the flashback to their birth and childhood, it was stated that they discovered their powers at some point. And their 100 % identical-ness, so to speak, was because they unconsciously started to imitate each other before they were even born. So I think they were born with their powers and not given them.

And I think such a power, to imitate others down to memories and/or powers, is something even Yhwach would be unable to give to anyone.