Zamora The Torture King uses mind techniques to focus his thoughts away from the pain he is inflicting upon himself.
His body, we believe, as become attuned to sharp objects penetrating skin and tissue. Because of this it does not go into “panic mode” and rush blood to the affected area.
This is why Tim does not bleed like the rest of us would, if we attempted such insane feats of self inflicted torture.
Because of this we do not believe he is genetically different to anyone else – this is a learned super power.