Genetics, Behavior, and Behavior-Genetic Interactions in Health Risk

The majority of behavioral traits and diseases are influenced by many genes (polygenetic), by some genes that affect more than one trait (pleiotropy), and by epistatic effects (genes interacting to create phenotypic variance). Additionally, epigenetic mechanisms highlight the plasticity of gene expression and proteins produced. Genes may not constitute a vulnerability factor per se but may rather be perceived as a factor of susceptibility – both according to its “negative” meaning (i.e., under specific circumstances, higher risk of developing some disease, or unfavorable behavioral trait) and its “positive” meaning (i.e., being also more sensitive to behavioral change during interventions). The field of behavioral genetics focuses on traits that appear to lie on continuous spectrums. Quantitative genetics (twin, family, and adoption studies) and molecular genetics (linkage analysis, GWAS) suggest some genetic links, but no single gene has been conclusively identified to affect specific disorders or conditions. In addition, environmental influences that interact with genetic determinants may be, themselves, filtered through the individuals’ memory, emotions, and personality.