Emily Post, I am not.
I do know that some view it as proper for ladies to sit with legs crossed at the ankles and not the knees. I think the real reason behind that was so one's calves would not be exposed in a "look at me" way in dresses.
I know I have better luck with proper posture in a chair if I have my legs crossed at the knees.
Both my furry girls have their own version of what it proper. Smokie sticks with the 'crossing at the ankles', while Mandy prefers the 'ankle under' method shown here. She is like my daughter in that way. Pearl can often be found sitting with one leg curled up under her. Not in a dress though! She wasn't raised in a barn. Not that I haven't tried, but Lee won't let us build a barn. He knows Pearl and I will just put more 4-legged things in it.
How do your 4-leggeds cross their legs?