He is born as a natural human with natural parents. His abilities is a combination of intensive training, steroids and intramuscular oil injections (think Greg Valentino). The oils are various back alley blends of cooking oil, motor oil and crude oil.
The blends have no scientific proven effect (probably not even mad scientific), but just works in his case. He is a result of experiments by some sort of back alley Dr Mengele, who is also a specialist in unsafe abortions. His fire abilities are because of combustion of injected hydrocarbons.
His biceps are the biggest in the world, 28 inches, probably exceeding your wife’s waist. His girlfriend is the amazon woman Sonja Johnson, who is probably more than twice as strong as you.