Is "ladylike" behavior a social construct, or are women naturally inclined to it?

For example, I'm more comfortable sitting with a bit of room between my legs, but most other women make the conscious decision to sit in a way that's more flattering. I won't spread myself out obnoxiously, but I won't sit with my back arched forward and my legs crossed either because it's unnatural and uncomfortable.

Another example is how some women force high-pitched, squeak sneezes, like they think it's cute or something. Is this forced behavior attractive to men?