I tend to think of it as physiology is all genetics. We canīt control our eye color no matter who our parents our for instance. Personality is all environment. Happiness isnīt genetics, itīs lots of hugs when you were young (yes thereīs a study on that lol. If you received a lot of hugs as a child you will generally be happier and more positive

). Personality and physiology can of course interact. Whoīs happy when theyīre sick? Well besides from all you youngsters who miss school