He was a towering figure in human molecular genetics, and his research contributions and academic mentorship transformed our understanding of the causative role of the genetic variation in phenotypic variation. Haig was born in 1937 to Armenian immigrants and was raised in Toledo, Ohio. His mother immigrated to the USA from Constantinople (now Istanbul) in 1920. His father, hailing from the Ottoman city Kayseri, survived a forced march from Anatolia to Aleppo, Syria, and life in a concentration camp during World War I. In 1917 his father escaped, via Damascus and Cuba, to Toledo, Ohio, where he joined his uncle in the Oriental rug business. Haig received his B.A. degree from Dartmouth College in Hanover, New Hampshire in 1959. He then continued as a medical student there for two years and completed an M.D. degree at Johns Hopkins School of Medicine in Baltimore in 1963. During his last year in medical school he met Barton Childs, who introduced him to human genetics and became his lifelong mentor. After two years of pediatrics training at the University of Minnesota Hospital in Minneapolis, Haig returned to Hopkins. In his first research experience, Haig worked on X-Chromosome dosage in the laboratory of Bill Young, a Drosophila geneticist. Then, as many other academically inclined physicians during the Vietnam war era, he entered the Public Health Service at the National Institutes of Health (NIH) as an alternative to military service. He joined the laboratory of Harvey Itano, where he began studies of hemoglobin synthesis at the dawn of the molecular biology revolution. Following this intensive, postdoctoral experience, Haig returned to Hopkins in 1969 as a faculty member in pediatrics. He received his first NIH grant the year after, beginning 50+ years of continuous NIH funding. As early as Norman Arnheim (left) and Haig Kazazian (right) in December 1988 at the Banbury Meeting, "Polymerase Chain Reaction." (Image courtesy of Cold Spring Harbor Laboratory Archives.