here's a scientific study i was reading indicating that "psychological well-being" (happiness?) is largely based on genetics. environment is largely "weak and non-significant". on one hand, it makes it seem like there's very little we can do to influence our own or others happiness. on the other hand, there's not much you can do to screw up the kids! :P

http://onlinelibrary.wiley.com/doi/10.1111/j.1467-6494.2012.00787.x/abstract