they are the person's own cells, made from their dna, but mutated.
a child is also made from a person's dna, but mutated. (primarily by combining with someone else's dna, but random mutation also plays a small role)
I don't think that's a scientifically valid use of the term mutated. Genetic combination vis a vis reproduction I would think is vastly differentiated from random mutation scientifically (and just common sensically).