In Bella yin and yang is very important. Usually you want to be yang. Because in Bella yin is the rich, noble, and high standard people. But if your yin your usually poor, sad, and have very few children or even none.
According to Greek mythology humans were originally created with 4 arms 4 legs & a head with 2 faces, but Zeus thought they had too much power so he split them into 2 people and made their goal in life to find their other half- soul mates