Thread:Valkryie247/@comment-4875214-20160924040817/@comment-28990978-20160924050847

You're right. Might I add that the tweet is from july 30, 2012. The lastest episode to that date was "Dipper vs. Manliness" (aired at july 20, 2012). There's no agreement about when do exactly the events of that episode take place, but the previous episode's events ("The Inconveniencing") took place in june 13 and 14 (see Timeline). What I mean is that we know for sure that Wendy already was 15 in june 14, 2012. For that to be possible, she must have been born between june 15 of 1996 and june 14 of 1997.

Now, assuming that if her birthday had been celebrated during the twin's vacations then we would have seen that in an episode, and because we didn't, then her birthday can't be between late may and september 1. So,  like AmericanButterfly said, assuming her birthday wasn't celebrated during the time span of the series, July 26 can't be her birthday and is not even close to it. Finally, if she was 15 al least from late may to september 1 of 2012, then she must have been born between september 2 of 1996 and late may of 1997.