That's something I never thought to even notice, now I'm curious. But imagine the storms if they did have 'sit styles'. Which cultural norms to adopt, and how sexist to be or not to be? I guess there could be cross legged either at knee or ankle for all genders, and legs not crossed nor held tightly together, just separate at the knees. That's going took very strange in short skirts though. All the ideas around assigned gender-specific modesty codes, double standards that mostly penalize women, the hot topic of what is and is not "manspreading" and so on.
I wouldn't want to be in charge of opening that can of worms!