The trauma of losing his wife and being Gau's father, who he sees as a demon child, drove him insane. An old woman in Nikeah's pub, when spoken to, will say that she helped deliver Gau thirteen years ago, and expresses sadness that he was thrown out onto the Veldt, believing him to be dead.
Gau's father lives north of the Veldt, and seems to think all his visitors are repairmen of some kind. If the player returns to his home in the World of Ruin with Gau and Sabin in the party, a scene will be shown of the party dressing Gau in fine clothes to present him to his father as alive. At this point, Gau's father gives his warped version of the events surrounding Gau's birth.
By his father's account, Gau's mother died in labor, giving birth to "a demon child". Terrified, Gau's father carried the child to the Veldt and abandoned it there, fleeing in terror. In the present Gau's father believes this to be a dream: he does not know Gau is his son, and seems to have forgotten he was ever married. He claims to still have nightmares about the "demon child", but compliments the well-dressed Gau on being a fine man. Though his father does not know him, that knowledge that he has a father makes Gau happy in spite of being rejected.