dave9000 you said "if someone doesn't look young, but is really really young in real life, would you still date them?" well that's why the show's not real life and this is fan made so even though it's still gross because they're twins they could very well be older than 12 here.
Well, now that you've decided to bring this back, I would like to make a point that the creator of this short gif is also the creator of "Gravity Falls as an anime". The little video is basically a remake of a scene of gravity falls with a different art style. Now what I would like to focus on is that the kids in the video is drawn exactly like the gif, not looking a year older or younger. And because the remake is basically just the show with a different look, it would be safe to assume that the kids in the video are the same age as the show making the gif kids the same age as the show, which is 12. A little stretch on the theory, but I've been thinking about this comment chain for a while, so no, I did not just dismiss taeminnieah's comment.
Even animated nipple biting
INCEST ≠ WINCEST
Unless you mean the other Gavin