Sisters

A sister is a woman or a girl who shares one or more parents with another individual, a female sibling.[1] 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.[2] 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.[3] 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.[4] In some quarters the term sister has gradually broadened its colloquial meaning to include individuals stipulating kinship.[5] In response, in order to avoid equivocation, some publishers prefer the usage of female sibling over sister.[6] 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.[7] 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.[8]

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.[9] Older sisters are more likely to play with their younger siblings.[10] Younger siblings display a more needy behavior when in close proximity to their older sister[11] and are more likely to be tolerant of an older sister's bad behavior.[12] 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.[13] 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.[14] Boys with older sisters were less likely to be delinquent or have emotional and behavioral disorders.[15] A younger sister is less likely to be scolded by older siblings than a younger brother.[16] The most common recreational activity between older brother/younger sister pairs is art drawing.[9] Some studies also found a correlation between having an older sister and constructive discussions about safe sexual practices.[17] Some studies have shown that men without sisters are more likely to be ineffectual at courtship and romantic relationships.[18]