arvetlighet

Arvetlighet refers to the proportion of variation in a trait within a population that is due to genetic differences among individuals. It is a concept used in genetics and evolutionary biology to understand how much of a particular characteristic, such as height, intelligence, or susceptibility to a disease, can be attributed to inherited factors. Heritability is not a statement about the determinism of a trait, nor does it imply that a trait cannot be influenced by environmental factors.

Heritability is typically expressed as a value between 0 and 1, where 0 means that all variation in the trait is due to environmental factors, and 1 means that all variation is due to genetic factors. For example, if the heritability of height is 0.8, it suggests that 80% of the observed differences in height among individuals in a population can be explained by their genetic makeup, while the remaining 20% is due to environmental influences like nutrition and health.

It is important to distinguish between heritability in a broad sense and heritability in a narrow sense. Broad-sense heritability includes all genetic variation, including additive, dominant, and epistasis effects. Narrow-sense heritability, on the other hand, only considers additive genetic effects, which are the ones that are directly passed down from parents to offspring and are crucial for predicting evolutionary responses to selection.

Heritability estimates are specific to a particular population and environment at a particular time. If the environment changes or the genetic makeup of the population shifts, the heritability of a trait can also change. Therefore, heritability is a population-level statistic and does not describe how much of an individual's trait is due to genes versus environment.