Perceptions matter - just ask your genes!
A newer field of study in biology is called social genomics. It is the study of how and when different genes are activated based on social interactions. On one level, it is very obvious that relationships affect our physiology. We can get anxious if someone is angry with us, which would show up as an increase in cortisol in our blood. But the study of social genomics goes much, much further and looks at all the genes that get activated. This provides clear evidence for a physiological mechanism of how lower levels of differentiation can negatively impact health. The same mechanism provides for how higher levels of differentiation can promote health and mitigate the effects of stress.