As the National Areata Foundation (NAF) explains, alopecia areata is known as a “polygenic disease”.
This means that, unlike a single-gene disease, both parents must contribute a number of specific genes in order for a child to develop it, says the NAF.
Because of this, most parents will not pass alopecia areata along to their children, explains the hair research body.
With identical twins — who share all of the same genes — there’s only a 55 percent chance that if one has alopecia areata, the other will, too, however.
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source: express.co.uk