Is Prosopagnosia Hereditary? Why It Sometimes Runs in Families

Developmental prosopagnosia is a condition in which someone has had difficulty identifying faces since early childhood, without a clear triggering event such as a stroke or head injury. Studies have reported cases where family members of a person with developmental prosopagnosia — parents, siblings, children — show a similar difficulty with face recognition. Some research examining extended families, including identical twins, has documented cases where multiple family members experience difficulty recognizing faces.

That said, this isn't simply a matter of "a diagnosis of developmental prosopagnosia being passed down to each family member." It's considered closer to the truth to think of face-recognition ability itself as having individual variation that is, to begin with, susceptible to genetic influence.

One way to examine how much genetic factors contribute to face-recognition ability is through twin studies. By comparing performance on face-recognition tests between identical twins raised in the same environment (who share nearly all their genetic information) and fraternal twins (who share about as much genetic information as ordinary siblings), researchers can infer a larger genetic contribution if identical twins show more similar scores to one another.

These twin studies have reported that much of the individual variation in face-recognition ability can be explained by genetic differences. This suggests that the ability to distinguish faces may be under relatively strong genetic influence, independent of visual acuity or general intelligence. However, this is a research finding about individual variation in the broader ability of "being good or bad at recognizing faces" — it does not mean that a specific pattern of inheritance (a particular gene or genetic pattern) has been identified for prosopagnosia itself.

Suggestive evidence of a genetic contribution doesn't mean developmental prosopagnosia is always passed from parent to child, or that it will necessarily appear in other family members just because one person has it. Genetic factors are thought to be one contributor among several to individual variation in face-recognition ability, and how they manifest varies widely — even within the same family, the degree of difficulty can differ substantially from person to person.

It's also thought that some cases of developmental prosopagnosia involve no genetic factor at all, or have no clear identifiable cause. Current research can't say that a specific gene or pattern of inheritance accounts for every case of developmental prosopagnosia. Having a family member with a similar difficulty is no reason to assume that you, or any other family member, will necessarily develop the same condition.