Why are all my friends so shocked that I don't eat grains?

Yeah, I'm only 13 years old but it's not like I'm on a diet. I'm just trying to be healthy. What's so unusual about that? I've been off grains for a few months now and I don't feel compelled to eat grains anymore, or any really any carbs aside from fruit. I eat a lot of fish, eggs, whole milk yogurt, and berries. But yesterday I was at my friends house for dinner and he was making pasta, and I told him I didn't eat grains and he looked pretty surprised and said he couldn't imagine my friend not eating grains. A couple of my friends will sometimes chase me around at lunch with granola and say "Evil carbohydrates - run away!" And I just have to wonder, why is this so surprising to everyone??? I mean, isn't it pretty much common knowledge carbs are bad for you? My mom stopped keeping any forms of sugar or pretty much anything carbier than fruit and nuts in the house a long time ago.