Yes, you are unless she only eats vegetarian jelly/jello/...J-lo.
The normal stuff is made from bone marrow and can be found in ordinary Jelly/J-lo, chewy sweets, mints, jam/conserves, some ice creams and milkshakes and loads of convenience food.
Buy your sister a t-shirt saying "Meat tastes like murder and murder tastes pretty God-damned good!"
Maybe your sister shoul be told that plants scream when they have leaves torn off.
EDIT: Hey hey hey hey hey....I've just been reading some of these Answers. And some of you people are just chronic self deceivers.
If you're a vegetarian you ONLY eat vegetables and animal products which don't come from a dead animal.
A vegan eats no animal products at all.
A true commited vegetarian or vegan will go to great lengths to find out what is suitable and wholesome for them to eat rather than just doing it as a fashion statement. Vegetarianism isn't something you can just pick up and drop every other day but still call yourself a Veggie. You either are or you aren't.
Personally, I love the taste of dead animal. Plants are still living things and I'd be more tempted to live on meat to preserve the plant life of the world.