To everyone saying this is incest, I have a theory why this might not be incest. If you think about it, if this Lewis was the same as Wilbur's dad, wouldn't Wilbur's dad remember Wilbur flirting which him and step in? What if Cornelius perfected his time machine and gave it the ability to travel to other dimensions? Then Wilbur could have used it to go to another dimension in which Lewis and Franny never got married and had Wilbur. Then that Lewis would technically not be Wilbur's father and it would not be incest. The Lewis in this picture could be an alternate dimension Lewis.
Welllllll, for all of you that is all like "they're father and son the fuuuuuq": Technicallyyy... well, when Wilbur comes back from the future to visit Lewis, Lewis hasn't... made?... Wilbur yet, so technically they're not related until Lewis is an adult and he and Franny... you know.