Answer
Rufus Wainwright's mother is Kate McGarrigle. She was a Canadian singer-songwriter, best known for her work with her sister Anna as the duo Kate & Anna McGarrigle. The pair released their debut album in 1975 and went on to release a total of eight studio albums. They were also inducted into the Canadian Songwriters Hall of Fame in 2006. Kate McGarrigle died of cancer in 2010.