Well I'm geeky, I wear glasses and I'm chubby... although I suppose being female helps to count me out of the completely stereotypical demographic.
Most of the gamers I know don't fit the stereotypical image, actually. I know hot gamers, ugly gamers, in-between gamers, tall gamers, short gamers... my brother's an enthusiastic gamer, and while he's a total geek he doesn't really look like one... until he opens his mouth and you realise that 'geek' is one of the few words you can use to truly, truly describe him.
Also, OP... I kinda reckon your sister's being a bit harsh. Lisa Foiles is really pretty, although I have to admit she's so pale that the gamer image really suits her. Yahtzee's pretty good-looking, I reckon, if you're comparing him to the general populace. That Guy With The Glasses isn't going to be winning any beauty contests, but I certainly wouldn't say he's zomgugly.