John "Jack" A. Weir was born April 5, 1916 in Saskatoon, Canada. He graduated from the University of Saskatchewan with a B.S. in 1937. In 1942, Weir received his Master's degree from Iowa State University. He interrupted his studies and enlisted in the Royal Canadian Navy from 1943-1945, where he served as a Lieutenant. After the war, Weir returned to Iowa State and completed his Ph.D in 1948.

Much of Weir's research focused on genetic resistance to infection in mice. Weir taught zoology at Iowa State University from 1945-1948. He was a professor in genetics at the University of Kansas from 1950-1984. Weir's achievements included the discovery of sex-ratio factor in mice, his development of inbred strains in mice, and other notable research regarding genetic resistance of mice to various conditions. Weir was awarded several prestigious research grants and traveled worldwide, lecturing at various symposiums and conferences.

In his personal life, John Weir married Ruth Rae Ward in 1946. They had two children, Muriel Ann, born in 1947 and Arnold Ward, born in 1950.

Weir was a member of the Genetics Society of America, the American Genetics Association, Sigma Chi, Phi Sigma, and several other organizations. He was an active associate and avid supporter of the Robert Burns Federation. Weir contributed many articles to several professional journals. Weir also had great interest in travelling, poetry, aviation, photography, and drawing. John Weir passed away in 1997.