Eric Molinksy is not the first artist to show what the cast of Rugrats might look like when they weren't babies, but full-grown adults. But he doesn't care for how those characters are interpreted when older. He was a storyboard artist for that show and drew them to look like "lumpy babies." They were ordinary babies and so, Molinsky claims, they'd likely look like ordinary adults:
It really bugs me — not the quality of the artwork, but the interpretation. We referred to them as lumpy babies for a reason. If we ever drew the Rugrats as being too cute, our executive producer would scold us. […]
So no. The Rugrats did not all grow up to be fashion models or self-confident hipsters. Especially not Chuckie. They probably grew up to be average if not slightly lumpy looking people — just like their parents. My best guess? In 2015, the Rugrats would look look something like this…
-via Nerd Bastards