No, the feral man is NOT the gunsmith's son, because the gunsmith's son was knocked into the river from the recoil of his repeater rifle, while the gunsmith was teaching him to shoot "properly". On the other hand, the feral man ran away from his home to get away from his "abusive" father. I just recently came upon the feral man in my playthrough, and hogtied him and was immediately attacked by two wolves. I killed them and lost honor! I thought that was strange until I read the feral man's journal found in his cave....then I felt really bad about what I'd done and I deserved the loss of honor! but I let the feral man keep breathing...least I could do!