My best friend has such pin-straight hair she literally can wash it and go, and it's long. It will dry perfectly straight. While I think straight hair day in and day out would be boring for me, I am endlessly jealous of how easy her hair is to do.
My hair is wavy when wet or productless, and my front layers will dry almost straight if I don't do anything to them. I would be perfectly happy styling it wavy, but as soon as I scrunch it at all, it goes curly. I feel like an oddity, because my productless pattern is vastly different than my styled pattern, but I don't have to manipulate it or use a ton of products to "force" it curly. My hair seems to be all or nothing - if I try to style it/let it dry as a wavy, it ends up frizzy and stringy. If I scrunch it, it spirals up and I get shrinkage and believe it or not it's frustrating because I'm trying to grow my hair out, and I'd like to wear it wavy sometime because it's longer that way.