Sister quartets

sisters murdered by the Dominican dictator Rafael Trujillo

American family R&B vocal group

alt=|thumb|OTMA from left to right, Maria, Tatiana, Anastasia and Olga Nikolaevna in 1914. OTMA was an acronym sometimes used by the four daughters of Emperor Nicholas II of Russia and his consort, Alexandra Feodorovna, as a group nickname for themselves, built from the first letter of each girl's name in the order of their births:

American girl group

Mexican serial killers

American gospel vocal group

four 19th century Scottish sisters, notable for their marriages to well-known men

American sibling group