[james_s_tayler]

It's almost 100% cultural I feel. At least Japanese people always attribute it to their culture and self concept of what Japanese do / how Japanese (and therefore themselves) behave.

If there are non-cultural factors I would think they contribute a fairly small amount.

But there's a light side and a dark side to the cultural factors. It has some seemingly unavoidable side effects.

Feels to me very much like a trade-off.