Behaviors are a very complex sequence of events, and heritability of any behavior is likely associated with multiple genes. | Photo: iStock

Q: How much do genetics play a role in my horse’s behavior?

A: In very simplified terms, heritability is the amount of difference in an observable trait that can be explained by genetic variation, as opposed to environmental and other influences. So you can see right away the problem we can have with discussing genetics and heritability of behaviors or temperaments in horses: the environmental differences in how horses are raised and handled can be so huge and are incredibly important in how behavior is expressed. Consequently, good heritability estimates require a large population of subjects, very similar definitions of the specific behavior or trait we want to measure, and the ability to control in real time or statistically the environmental differences.

Behaviors are a very complex sequence of events, and heritability of any behavior is likely associated with multiple genes, which might also be linked to genes for other physical and behavioral traits. Since domestication, it seems clear that over many years horses were (and still are) largely selected and bred for the anatomical and physiological characteristics best for their particular environments and uses