The McGuire Sisters were a singing trio in American popular music. The group was composed of three sisters; Christine McGuire (born July 30, 1926), Dorothy McGuire (born February 13, 1928), and Phyllis McGuire (born February 14, 1931). Among their most popular songs are "Sincerely" and "Sugartime".

The McGuire Sisters were stars of radio and television and were the most popular sister group of the 1950's
~Source: Wikipedia