Final answer:
Happiness is significantly but not entirely heritable, with research such as the Minnesota Study of Twins Reared Apart indicating a genetic component alongside environmental and epigenetic influences.
Step-by-step explanation:
Genetic research indicates that happiness is significantly but not entirely heritable. This is illustrated by studies such as the Minnesota Study of Twins Reared Apart, which evaluated the personalities of identical and fraternal twins. It was observed that certain personality traits, including those related to happiness, have a heritability ratio higher than 0.50, suggesting a notable genetic component.
Yet, heritability does not mean these traits are determined solely by genes; environmental factors and epigenetic influences also play a critical role. For instance, while factors like leadership and resistance to stress have genetic underpinnings, their expression and impact on a person's happiness can be modified by life experiences and circumstances. Therefore, while heritability signifies the proportion of variance in happiness due to genetics, it is not exclusive, as environmental and epigenetic factors also contribute significantly.