I can buy 12 as the age of Shaggy, Daphne, and Freddy. I just always assumed that Velma skipped a few grades and that's why she was so much smaller/younger-looking than every other kid we see in the show.


I think it was done that way because most of the Pup plots couldn't move forward if any of the kids had competent parents. But...yeah, they really should have said that the ski lodge belonged to Daphne's aunt or something so at least the kids wouldn't be staying in a B&B owned by a freaky couple they've never even met before.