An idea that popped into my head. Perhaps he doesn't have any powers besides being a genius mad scientist. He's always known that there are people out there who do and in incredibly jealous of them. He does experiments on them to figure out how they get their powers. Then one day while he is doing experiments on Clara and her birth parents, he ends up killing them in the process, which has happened many time before and after that.
Another idea. What if Clara's birth parents have no powers and they take her to the mad scientist to get her 'fixed'. But, he kills them instead, so he can do experiments on her.
As far as the name goes, I thought it might be interesting to name him Igor. After all the years of watching his master do experiments we learn that Igor is a genius who does his own experiments.
I think Hendrix should be the adoptive parents name, unless they adopted her when she was older.