Is there any precedent for this? I am not overly familiar with Fallouts Lore though I am a Lore junkie. Just not that deep into Fallout's Lore yet.

I don't necessarily mean it was bred by a Super Mutant pairing with a human as I am aware Super Mutants are sterile. But could the FEV have caused someone to develop a kind of half mutant look? Or I guess a better explanation would be limited amounts of FEV mutation.

The way i think about it, they would look very humanoid and be only slightly bigger than a Normal Human. The said individual would have most of the benefits of a Super Mutant and a very small amount of insanity. Almost unnoticeable.

From the Fallout Wiki I got this. Now I don't know how reliable the Fallout Wiki is though so feel free to admonish my interpretations.
"They are much taller, bulkier and muscular than pure strain humans, have (mostly) green, gray, or yellowish skin, are immune to disease and radiation, and are gifted with superhuman strength and endurance. Although they are completely sterile, the rapid regeneration of their cells caused by FEV makes them virtually biologically immortal (but not immune to death from injury)."

I feel like that would be an interesting Roleplay. I have no clue if there is mod that does that or not. Creating a half mutant race that is.