[travisp]

It's important to understand that the way many people understand heritability usually isn't what most scientific researchers mean when they say "heritable."

> Heritability is an important concept in quantitative genetics, particularly in selective breeding and behavior genetics (for instance, twin studies). It is the source of much confusion due to the fact that its technical definition is different from its commonly-understood folk definition. Therefore, its use conveys the incorrect impression that behavioral traits are "inherited" or specifically passed down through the genes.

...

> Heritability measures the fraction of phenotype variability that can be attributed to genetic variation. This is not the same as saying that this fraction of an individual phenotype is caused by genetics. For example, it is incorrect to say that since the heritability of personality traits is about .6, that means that 60% of your personality is inherited from your parents and 40% comes from the environment. In addition, heritability can change without any genetic change occurring, such as when the environment starts contributing to more variation...High heritability of a trait, consequently, does not necessarily mean that the trait is not very susceptible to environmental influences. Heritability can also change as a result of changes in the environment, migration, inbreeding, or the way in which heritability itself is measured in the population under study. The heritability of a trait should not be interpreted as a measure of the extent to which said trait is genetically determined in an individual.

https://en.wikipedia.org/wiki/Heritability

[Gh0stRAT]

The example I heard that really drove this point home for me is that humans almost all have 10 fingers, and the ones who don't are almost entirely due to the environment (frostbite, table saw accidents, etc) so the number of fingers on a human hand is actually a low-heritability trait.

[username90]

Did they actually do a twin study on finger count, or are you making things up? Otherwise you can't know for sure. For example, I'd bet that propensity to lose limbs correlate strongly with willingness to engage in risky activities, and risk taking has a significant genetic component according to other studies.

[travisp]

Even if you're right (and finger count is a common example for students to teach the concept of heritability), this will run counter to what people think when they hear "heritability."

Most people wouldn't think "number of fingers is heritable because their propensity for risk taking is genetic" they would say it's because the number of fingers we are born with is genetic, which would be a mostly incorrect reason for any heritability statistic on number of fingers. I think your possible explanation about why number of fingers might be fairly heritable only reinforces my point about what most people understand about heritability.

And, for the same reason, while risk taking seems to be heritable, we don't know the particular genetic contribution to risk taking.