**1.3 Trait theory**

This theory sees happiness as a stable personality trait, rather than a variable state. This character happiness is seen to root in genetic endowment and early experience and to result in a 'set-point' level around which happiness can vary a bit across ups and downs. The macro-level variant of this theory holds that average happiness in nations is a matter of national character, which roots in culture and history. In this view, average happiness in nations will change only in the very long-term.

A variant of this theory holds that the set point is typically around 7.5 on a scale of 0–10, which level is homeostatically defended, like our body temperature [5]. In that view, average happiness will typically vary around that level and will be lowered only if homeostatic defense fails, like when we are unable to keep warm.
