A sister is a woman or girl who shares one or more parents with another individual. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to refer to non-familial relationships. A full sister is a first degree relative.
The English word sister comes from Old Norse systir which itself derives from Proto-Germanic *swestēr, both of which have the same meaning, i.e. sister. Some studies have found that sisters display more traits indicating jealousy around their siblings than their male counterparts, brothers. In some cultures, sisters are afforded a role of being under the protection by male siblings, especially older brothers from issues ranging from bullies or sexual advances by womanizers. In some quarters the term sister has gradually broadened its colloquial meaning to include individuals stipulating kinship. In response, in order to avoid equivocation, some publishers prefer the usage of female sibling over sister. Males with a twin sister sometimes view her as their female alter ego, or what they would have been like, if they had two X chromosomes. A study in Perth Australia found that girls having only youngers brothers resulted in a chastity effect, losing their virginity on average more than a year later than average. This has been hypothesized as being attributed to the pheromones in their brothers' sweat and household-related errands.
Various studies have shown that older sisters are likely to give a varied gender role to their younger siblings as well as being more likely to develop a close bond with their younger siblings. Older sisters are more likely to play with their younger siblings. Younger siblings display a more needy behavior when in close proximity to their older sister and are more likely to be tolerant of an older sister's bad behavior. Boys with only an older sister are more likely to display stereotypically male behavior, and such masculine boys increased their masculine behavior with the more sisters they have. The reverse is true for young boys with several sisters, as they tend to be feminine, however, they outgrow this by the time they approach pubescence. Boys with older sisters were less likely to be delinquent or have emotional and behavioral disorders. A younger sister is less likely to be scolded by older siblings than a younger brother. The most common recreational activity between older brother/younger sister pairs is art drawing. Some studies also found a correlation between having an older sister and constructive discussions about safe sexual practices. Some studies have shown that men without sisters are more likely to be ineffectual at courtship and romantic relationships.
- Awan and Azura, daughters of Adam and Eve
- Mary I of England and Elizabeth I of England, royalty
- Princess Augusta of Great Britain, Princess Elizabeth, Princess Louisa, and Caroline Matilda of Great Britain
- Princess Feodora of Leiningen and Queen Victoria, royalty
- Victoria, Princess Royal, Princess Alice, Princess Helena, Princess Louise, Duchess of Argyll, and Beatrice, Princess Henry of Battenberg, royalty
- Louise, Princess Royal, Princess Victoria and Maud of Wales
- Princess Margaret of Connaught and Princess Patricia of Connaught, royalty
- Caroline, Princess of Hanover and Princess Stéphanie of Monaco
- Elizabeth II and Princess Margaret, Countess of Snowdon, royalty
- Princess Alexandra, 2nd Duchess of Fife and Princess Maud, Countess of Southesk, royalty
- Margrethe II of Denmark, Princess Benedikte of Denmark, Anne-Marie of Greece, royalty
- Princess Beatrice and Princess Eugenie
- Princess Isabella of Denmark and Princess Josephine of Denmark
- Tamar, Toni, Towanda, Traci, and Trina Braxton, known as The Braxtons
- Jacqueline Bouvier Kennedy Onassis and Lee Radziwill
- Barbara Bush Coyne and Jenna Bush Hager
- Geraldine, Josephine, Victoria, Jane, and Anette Chaplin, actresses
- Liz and Mary Cheney
- Mary and Eliza Chulkhurst, conjoined twins that are known as the Biddenden Maids
- Diana Churchill, Sarah Churchill, Marigold Churchill, and Mary Soames, daughters of Winston Churchill
- Jackie Collins, author and Joan Collins, actress
- Elizabeth Parke Custis Law, Martha Parke Custis, and Eleanor Parke Custis Lewis, granddaughters of Martha Washington
- Annie Elizabeth Delany and Sarah Louise Delany, the subjects of Having Our Say (1993)
- Hilary Duff, actress, and Haylie Duff, singer
- Eva, Magda, and Zsa Zsa Gabor, actresses and singers
- Melissa and Sara Gilbert, actresses
- Ilona and Judit Gófitz, conjoined twins
- Karenna, Kristin, and Sarah Gore, daughters of Al Gore
- Sarah Moore Grimké (1792–1873) and Angelina Emily Grimké (1805–1879), known as the Grimké sisters, the first American female advocates of abolition and women's rights
- Kamala and Maya Harris, lawyer
- Mariel Hemingway and Margaux Hemingway
- Abby and Brittany Hensel; conjoined twins
- Paris and Nicky Hilton, socialites
- Maureen "Rebbie" Jackson, La Toya Jackson, and Janet Jackson, members of the Jackson family
- Khloe Kardashian, Kim Kardashian, Kourtney Mary Kardashian, reality TV stars
- Yolanda and Bernice King, daughters of Martin Luther King Jr.
- Beyoncé and Solange Knowles
- Caroline Manzo and Dina Manzo, reality TV stars who married brothers Albert and Tommy Manzo
- Millie and Christine McCoy, conjoined twins
- Brooklyn and Bailey McKnight; American YouTubers
- Catherine, Duchess of Cambridge, member of the British royal family and Pippa Matthews, English socialite, author and columnist
- Grand Duchess Olga Nikolaevna of Russia, Grand Duchess Tatiana Nikolaevna of Russia, Grand Duchess Maria Nikolaevna of Russia and Grand Duchess Anastasia Nikolaevna of Russia, also known by the acronym OTMA, daughters of the last Emperor of the Russian Empire
- Patricia "Tricia" Nixon Cox and Julie Nixon Eisenhower, daughters of Richard Nixon
- Ashley and Mary-Kate Olsen, also known as "The Olsen Twins", twin actresses and fashion designers, and Elizabeth Olsen, actress
- Savannah and Isla Phillips, members of the British royal family
- Anita Pointer, Bonnie Pointer, Issa Pointer, June Pointer, Ruth Pointer, and Sadako Pointer, at various times members of the singing group known as The Pointer Sisters
- Kim Richards and Kyle Richards, actresses and reality TV stars
- Elizabeth Rockefeller Strong, Alice Rockefeller, Alta Rockefeller Prentice, and Edith Rockefeller McCormick
- Grace Roosevelt and Ellen Roosevelt, American tennis players
- Jessica and Krystal Jung, Korean-American singer-songwriters and actresses
- Angelica Schuyler Church, Elizabeth Schuyler Hamilton, and Peggy Schuyler
- Jessica Simpson and Ashlee Simpson, singer-songwriters
- Britney Spears, singer, and Jamie Lynn Spears, actress
- Lady Sarah McCorquodale, Jane Fellowes, Baroness Fellowes, and Diana, Princess of Wales members of Spencer family
- Johanna, Martina, Maria, Hedwig, Agathe, Rosemarie, and Eleonore ("Lorli") Von Trapp, daughters of Georg von Trapp
- Venus Williams and Serena Williams, tennis players known as Williams sisters
Fictional works about sisters
- What Ever Happened to Baby Jane? (1962)
- Hannah and Her Sisters (1986)
- Hanging Up (2000)
- Frozen (2013)
- Little Women (2019)
- Little Women
- Laura Lee Hope's Bobbsey Twins novels, which included two sets of fraternal twins: 12-year-old Nan and Bert, and six-year-old Flossie and Freddie
- In Her Shoes (2002), novel
- #Toots (2019), novel
- Hope & Faith, American sitcom
- Sisters (TV series)
- What I Like About You, TV series
- Sister, Sister, TV series
- "Definition of sister in English by Oxford Dictionaries". Oxford Dictionaries. Retrieved 2019-05-24.
- Mufwene, Salikoko S. "The pragmatics of kinship terms in Kituba." (1988): 441–454.
- Volling, B. L.; McElwain, N.L.; Miller, A.L. (2002). "Emotion Regulation in Context: The Jealousy Complex between Young Siblings and its Relations with Child and Family Characteristics". Child Development 73 (2): 581–600.
- Handbook of Cultural Psychiatry — Page 67, Wen-Shing Tseng – 2001
- van der Burghe, Pierre (1987). The Ethnic Phenomenon. p. 27.
- Olshewsky, Thomas (1969). Problems in the philosophy of language. p. 286.
- McCallum, Robyn. "Other Selves: subjectivity and the doppelganger in Australian adolescent fiction. Example of the sister in a sentence "The sisters live in the convent at Lafayette Towers." Writing the Australian child: Texts and contexts in fictions for children (1996): 17–36.
- "Do Brothers Stall Their Sisters' Sex Lives? | Psychology Today Australia". Psychology Today.
- Gender — Page 53, Leanne Franklin – 2012
- Play from Birth to Twelve: Contexts, Perspectives, and Meanings, Doris Bergen 2015
- Sisters and Brothers — Page 78, Judy Dunn – 1985
- The Corsini Encyclopedia of Psychology and Behavioral Science, Volume 4, Charles B. Nemeroff, 2002 p 1524
- Gender Development — Page 300, Lynn S. Liben – 2009
- Gender Development, Sheri A. Berenbaum, 2013
- Advances in Child Development and Behavior, Volume 26, p 161, 1996
- He & she: how children develop their sex role identity, Wendy Schempp Matthews – 1979 p 162
- Handbook of Adolescent Psychology, Contextual Influences on Adolescent Development, Laurence Steinberg, PhD – 2009 p 61
- Leventhal, Gerald S. "Influence of brothers and sisters on sex-role behavior." Journal of Personality and Social Psychology 16.3 (1970): 452.
- The dictionary definition of sister at Wiktionary