Good point, Rollo. For myself, I think attitude is partly nature and partly nurture, part mindset and part body chemistry, so intertwined that it's pretty hard, in most cases, to work out what comes from where. There are obvious exceptions, like the type of depression that responds well to chemical treatment alone, but a lot of it is also a product of culture (both of the family and the general society) and of breadth and depth and nature of life experience. Even then, people can draw different conclusions from the same data, and hence develop different mindsets.
My husband often remarks that he is surprised by my worldview, and thinks that said worldview would fit better with the life he has lead than does his own worldview, given that he has largely led a reasonably easy life, as lives go, but is a total cynic, very cautious about other people and very unwilling to risk being happy. His life has included a few awful things, but most of it has been good and pretty safe. Whereas most of mine has been pretty tough, but it just doesn't seem to have affected me in the same ways - I will trust people until they give me good reason not to, and I persist in bobbing to the surface again when life rolls over me. No idea why, just stubborn, I guess, and unwilling to surrender. Who really knows how people work?
Also, that thing about Jupiter's moons is simply awesome!
