William Jackson (Jack) Schull (17 March 1922 – 20 June 2017) was an American geneticist and Professor Emeritus of Human Genetics at The University of Texas Health Science Center at Houston.

His scientific contributions include studies on the effects of ionizing radiation on human health, the role of heredity and the interaction of heredity and environment in the etiology of chronic disease, the effects of inbreeding in human populations, the mechanisms of adaptations to hypoxic conditions, and the genetic epidemiology of populations burdened by chronic diseases associated with low socio-economic status.

Schull received a Bronze Star for medical services in the fight to recover Baguio on the island of Luzon, Philippines in 1945 during World War II.

On 7 September 1946, Schull married Victoria (Vicky) Margaret Novak at Saint John the Divine Catholic Church in Milwaukee.

[2] Chief among his earliest scientific interests are a large group of studies on human consanguinity (inbreeding) that spanned half a century of research and a wide geographical range.

[4] For his studies in Japan, information concerning thousands of people and entire communities was obtained on such items as birth date, birthplace, education, occupation, religion, date of marriage, previous marriages, consanguinity, number of persons in the household, size of the house, diet, income, land holdings, attitudes toward reproduction, and a pregnancy-by-pregnancy listing of the reproductive performances of the husband and wife in this and previous unions.

In 1981, Schull and colleagues summarized thirty-four years of study on the genetic effects of the atomic bomb,[5] followed by a series of papers on the causes of mortality of A-bomb survivors.

In the 1980s, Schull and colleagues pioneered a survey and an in-depth study on obesity, diabetes, gallbladder disease, hypertension, and other cardiovascular and metabolic afflictions among Mexican-Americans in Starr County, Texas.