Tiefling genetics

Ok so, tifling are decendentd of friends, including devils, but to MY knowledge devils can't produce, also if they(or any other fiend) could, and breed with a human/(any humanoid, mabey???) they apparently wouldn't make a tiefling, they'd make a cambion. Would a human cambion cross breed be a teifling or a half cambion?

I've heard a humanoid with any feind ansestory would be a teifling, do would a teifling plus a human make a half teifling, or a full teifling?