It CAN be a jewish name but it is a German name either way. Some Steiner's are Catholic's,some are Jewish,some are protestant! Felix Steiner was a Waffen SS General in WW2. My grandmother's mother father's surname was Steiner but they were Catholic.
Most of the Steiner's I've met in my life (not counting my family members) are Jews, but it is not singularly a Jewish name.
Somebody knows the origin of Fross surname?