Ma's dad, whom we only know as Grandpa, has a more difficult time dealing with his daughter's return than any of her other family members have. Actually, it's not her return that bothers her: it's Jack. When he sees Jack, Grandpa says, "I can't be in the same room. It makes me shudder" (4.1124). You read that right: he calls Jack it.
Grandpa can't get past the fact that Jack exists because his daughter was kidnapped and raped. Jack is a product of rape, but his Ma doesn't love him any less. She prefers to think of Jack as a gift from God rather than the result of tragedy and abuse. But Grandpa can't look past that. We only see him for a couple of pages, and we're not sure if he'll never know how awesome his grandson is, despite his horrific origins. After all, don't all superheroes have tragic origin stories?