His father, Dr. Paul Kasirer, was a medical doctor of Jewish heritage who passed away in 1999 (The Globe and Mail).
His mother was Patricia Heeney, daughter of Arnold Heeney, a Rhodes Scholar who served as principal secretary to Prime Minister Mackenzie King (1938-1940), Clerk of the Privy Council and Secretary to Cabinet (1940-1949), and twice served as Canada's ambassador to the United States and to NATO (The Globe and Mail; The Canadian Encyclopedia).
Kasirer grew up in Montreal and is perfectly bilingual in English and French (Department of Justice).
He is married to Jane Mappin, a dancer, choreographer, interpreter, and dance teacher; the couple has three children, including a son who became a Rhodes Scholar studying medicine at McGill and two daughters who studied at Oxford (The Globe and Mail; Norton Rose Fulbright).
Resides in Montreal's Outremont neighbourhood and is a collector of Canadian paintings (Norton Rose Fulbright).