I'm not the best to ask, since I'm not a DC comic fan, but based on my memory of The Flash (and my memory should be taken with a grain of salt ), many of the villains are meta-humans, who are humans who gained powers due to the explosion of the particle accelerator that Dr. Wells was working on. Other villains like Zoom and Savitar seem to have a different origin (and to be honest, I don't remember ).
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