Final answer:
Heritability of happiness is an aspect of behavioral genetics that indicates a substantial genetic contribution to individual differences in well-being, supported by findings from twins studies.
Step-by-step explanation:
The heritability of happiness, or the fraction of subjective well-being variation that can be attributed to genetic differences, plays a significant role in behavioral genetics. Twins studies, especially the Minnesota Study of Twins Reared Apart, support the notion that genetics contribute significantly to personality traits, including subjective well-being.
Identical twins have shown high similarity in these traits regardless of whether they were raised together or apart, indicating a strong genetic component. Moreover, heritability affects a population's susceptibility to evolutionary forces, as phenotypic variations that are more heritable are more likely to be acted upon by these forces.