Soaking beans?!
Answers: I'm trying to cook some dried kidney beans. I soaked them first and only maybe 80% of the beans got larger. Why did the others stay the same size?
The beans that "stayed the same size" only LOOKED that way; they all absorbed a bit of water.
When you soak dried beans, they absorb water very passively, because there's no heat involved. Soaking is really meant to soften the beans' skins, which will speed up absorption when they're eventually cooked.
Also, since beans are a natural product, there will be some variance in size, skin thickness, absorption time, and so forth.
How long did you soak the beans for? My grandma use to soak the beans overnight... maybe they didn't have enough time to absorb the water.
soak ovenight, they will be "less" gassey also.