About 1 out of 4 people of Ashkenazi Jewish heritage is a carrier of one of these genetic conditions, most commonly of Gaucher disease, cystic fibrosis, Tay-Sachs disease, familial dysautonomia, or Canavan disease.footnote1

https://www.uofmhealth.org/health-library/tv7879

Edit found gold from Goldstein

"Ashkenazim became what scientists call an “endogamous group,” which is another way of saying that they have been sleeping with their cousins for a thousand years."

https://jewcy.com/featured/brilliant_resistant_to_hiv_and_more

About 1 out of 4 people of Ashkenazi Jewish heritage is a carrier of one of these genetic conditions, most commonly of Gaucher disease, cystic fibrosis, Tay-Sachs disease, familial dysautonomia, or Canavan disease.footnote1

https://www.uofmhealth.org/health-library/tv7879