Wiki article if you need a primer (or need to get to sleep in a hurry): https://en.wikipedia.org/wiki/Heritability
I suspect it's common for people to conflate heritability and heredity (inheritance).
Heredity is the passing on of traits via genes. (This is the easy one that everyone understands.)
Heritability is the degree to which genes are responsible for variations in traits.
Robert Sapolsky gives two examples to illustrate how intuition gets us confused on this:
1. The heritability of the number of fingers on one of your hands is virtually zero. Variation in the numbers of fingers on your hand is very, very rarely caused by genes. People are most likely to have a different number of fingers due to environmental factors (like using a bandsaw with your eyes closed). (timestamped link to video).
2. Suppose you have a hypothetical society in which women always wear earrings and men never do. In that society, one's sex chromosomes are 100% responsible for one's earring-wearing behaviour, therefore earring-wearing has 100% heritability. (timestamped link to video)
This shows that heritability is a completely different idea than heredity, and if we laypersons conflate the two when talking about, say, heritability of IQ in humans, then we are guaranteed to come to the wrong conclusions.
I suspect it's common for people to conflate heritability and heredity (inheritance).
Heredity is the passing on of traits via genes. (This is the easy one that everyone understands.)
Heritability is the degree to which genes are responsible for variations in traits.
Robert Sapolsky gives two examples to illustrate how intuition gets us confused on this:
1. The heritability of the number of fingers on one of your hands is virtually zero. Variation in the numbers of fingers on your hand is very, very rarely caused by genes. People are most likely to have a different number of fingers due to environmental factors (like using a bandsaw with your eyes closed). (timestamped link to video).
2. Suppose you have a hypothetical society in which women always wear earrings and men never do. In that society, one's sex chromosomes are 100% responsible for one's earring-wearing behaviour, therefore earring-wearing has 100% heritability. (timestamped link to video)
This shows that heritability is a completely different idea than heredity, and if we laypersons conflate the two when talking about, say, heritability of IQ in humans, then we are guaranteed to come to the wrong conclusions.