Emerging research concludes that genetics make us susceptible to traits and behavior, but susceptibility is not destiny (Sinha 2004). In other words, "I can't help it; I was born this way" is not an excuse for bad behavior and stupid decisions.
In Psychology Today, Sinha (2004) summarized critical genetics studies as follows:
- Individual choice influences gene expression and brain development.
- Experience influences which genes are activated and how.
- Internal and external factors shape the individual.
- Genes make us susceptible to certain traits, but our thoughts, actions, behaviors, and environment influence the activation and suppression of genetic switches.
- Inherited traits are contingent on individual choices and environmental influence.
Examples of genetic susceptibility not being inevitable include:
- Identical twin studies show that twins with identical DNA raised in the same environment tend to develop different personalities (Fraga, et al., 2005; Poulsen, Esteller, Vaag, and Fraga 2007).
- Studies on alcoholic monkeys found that nurturing and disciplined environments decrease adverse effects from genetic triggers for alcoholism (Klaus-Peter, 2005).
Sinha (2004) concluded that there's a 50/50 split between how genes and experience influence our behaviors and personality. In short, regardless of our genetic tendencies, choice, and environment influence genetic expression.
How does understanding that our choices and environment influence our behaviors as much as our genetics help us understand opportunities for personal growth?
Klaus-Peter, L. (2005) Alcohol dependence and gene x environment in emotion regulation: Is serotonin the link? European Journal of Pharmacology 526 (2005) 113 – 124.
Fraga, M.F. et al. (2005) Epigenetic differences arise during the lifetime of monozygotic twins. PNAS, 102:10604-9.
Poulsen P., Esteller M., Vaag A., Fraga M.F. (2007) The Epigenetic Basis of Twin Discordance in Age-Related Diseases. Pediatric Research, 61: 38R-42R (subscription required).