Sisters

A sister is a woman or girl who shares one or more parents with another.[1] 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]