Just sitting on the ground crossed legs difficult

What do they call this popular sitting that everyone does regardless of martial art, yoga or sport. Its not the lotus position, even though it looks like it, and the feet are not put inside the thighs. Its a dumb question but believe or not I don't know what its called.



The annoying thing is I can't do it. It annoys me because there are situations when people all sit on the floor likes this as if its comfortable but its not for me. And I can't keep my back up straight in this position either.



I don't think its about flexibility or doing yoga, since I've seen a lot of people do it with ease even though they don't practice sports or yoga. So why do I find it so difficult. Is there genetic conditions where some people just can't sit in this very popular position? Is it to do with the shape of my legs? Hips?



Maybe someone knows what I'm talking about?



Long story short I would like to increase flexibility in the hips that would allow me to sit comfortably in this position. But I want to find out what this is first.



Thanks