Final answer:
Factors influencing gene expression are primarily studied in the field of epigenetics. This area examines how environmental exposures can impact gene expression and contribute to heritable traits. Evolutionary psychology also deals with genetics but focuses on adaptive psychological traits over time.
Step-by-step explanation:
The factors that affect how our genes are expressed are involved primarily in the scientific study of epigenetics. This field explores how environmental factors and other external influences can alter gene expression without changing the underlying DNA sequence. Epigenetic mechanisms can lead to differences in physical traits, behaviors, and risk factors for various diseases, which are sometimes heritable across generations.
Evolutionary psychology also intersects with genetics, as it studies universal patterns of behavior and cognitive processes that have evolved over time. It hypothesizes that certain psychological traits may have been adaptive and contributed to reproductive success. However, epigenetics is the more direct study of changes in gene expression in an individual's lifetime and is at the heart of examining how genotypes (the genetic makeup) manifest as phenotypes (observable characteristics).
Both evolutionary psychology and epigenetics contribute to our understanding of how genes influence not just physical attributes but also behavioral traits and psychological tendencies. Researchers in these fields investigate the complex interplay between genetic predispositions and environmental factors to understand human behavior and evolution.