Stress is one of the biggest causes of epigenetic changes. We are not meant to endure stress in the long term or live in survival mode. No living creature is designed to live in survival mode.
Living in survival mode means living in our reptilian brain. We can only focus on 3 things: Physical body(Am I okay?), Enviroment(Is it safe?), and Time(How long will this threat be hanging over me). These things make us less spiritual, mindful, and less aware because it trains us to be more self absorbed and focused on our bodies and material things. Keeps us in the survival energy centers that promote selfishness. Makes us obsess over time, never enough time. We become materialists and define reality with our senses. The me first mentality is reinforced and self importance becomes a way of being.
Meditation can change your epigenetics in just one session. As you get better at it, you will receive more benefits. This changes over 1,000 genes and improves your immune system.
Source: You Are The Placebo by Dr Joe Dispenza