Does your LO sit like this? (with their legs flipped out, making them the middle of the W). My 3 year old did for awhile around 1.5-2, but I gently encouraged her to sit criss cross and she would.

However, my 12 month old has started sitting like this and aside from constantly changing her legs, there isn't much I can do yet because she doesn't understand to change her position!

A member of my extended family sat like this as a child and his stance is VERY obvious as an adult because of it. Both his legs turn out!