>>719739747
When Dess was still around she and Asriel were bigger (teenaged) while Kris and Noelle were small younger kids. Dess and Asriel were probably roughly the age that Kris and Noelle are now, old enough to have a part-time job and be thinking about college.
Even if Dess was on the younger side of plausible estimates it still has to have been a few years since she disappeared, long enough for Kris and Noelle to have grown up from young kids to teens.
>>719739757
She has tons of well-used sporting equipment including stuff like ice hockey and paintball, outdoorsy gear implying she would camp out in the woods alone, she was into MTV and has instruments and made-up posters implying she had or wanted to be in a band, she has "scary" games and movies, and she has a weed stash.
These are things you find in an older teenager's room. I don't know who's imagining a 12 or 13 year old girl wearing flannel or leather jackets.