This one was a surprise to me- I always knew that it was a big no no to sit in a matter which meant anyone could see the sole of your shoe- a sign of disrespect (just as to hit someone with your shoes/slipper is a highest form of disdain).
However, I hadn't realised that you shouldn't sit crossed legged at all, esp. in front of your father, mother or someone else older than yourself! Our teacher makes his sons stand up when he comes into the room, and sit 'properly' in his presence- they get a cuff round the ear if they cross their legs in front of him!!!
Seemingly its ok for a woman to stay crossed legged when man enters the room- but not if another woman does……. I dread to think how many women (and men) I have unwittingly offended in my time here (or indeed how many jobs I may not have got because of the way I was sitting!!!!)