I've always felt uncomfortable with spreading my legs (you know, like a V) while sitting, so generally my knees have always stayed together. But after a while my inner calves start hurting. Nothing horrible, but enough to make me feel uncomfortable. I can try to cross legs (which eventually hurts my knees and can in the long term damage the back)/sit indian-style (which is uncomfortable on a chair)/put a foot under my other knee (which can damage the bak too)/stand up/do something else but it's generally not much better.
So it basically means I can't sit "up straight" for a long time. Why is this ? Could it be because my parts are being an obstacle (but I doubt it, because they don't hurt at all... Actually, they rarely ever hurt ; I'm not even very sensitive to "kicks in the nuts") ? Or something about my hips being small ?
And it's certainly not the lack of habit, as I've done this forever.