Milton Wexler was born August 24, 1908 in San Francisco and raised in New York City. He attended Syracuse University (Class of 1929), studied law at New York University, and received a PhD in psychology from Teachers College, Columbia University. He served in the United States Navy during World War II. After returning to civilian life, he treated patients with schizophrenia at the Menninger Foundation in Topeka, Kansas. He then went on to a career treating notable creative figures in Hollywood and was reportedly the first non-psychiatrist practicing psychoanalyst.

In 1936, Milton married geneticist Leonore Sabin and had two daughters, Alice and Nancy. After they divorced in 1962, Leonore was diagnosed with Huntington disease prompting him to established the Hereditary Disease Foundation (HDF) in 1968 to support research in treating the disease and other genetic disorders. He recruited celebrities to help support the organization and served as chairman into the 2000s. His daughter Nancy, a professor of neuropsychology, collaborated on research resulting in the identification of the genetic marker causing Huntington disease. His daughter Alice, a historian and author, interviewed her father and key individuals involved in the HDF, resulting in her books, Mapping fate: a memoir of family, risk, and genetic research (Random House, 1995) and The analyst: a daughter's memoir (Columbia University Press, 2022).

Leonore Sabin Wexler died in 1978. Milton Wexler died of respiratory failure on March 16, 2007 at age 98.