Sibling

Two Sisters by William-Adolphe Bouguereau

Brothers Prince Edward V of England and Prince Richard of Shrewsbury, 1st Duke of York.

A sibling is a brother or a sister; that is, any person who shares at least one of the same parents.

In most societies throughout the world, siblings usually grow up together and spend a good deal of their childhood with each other. This genetic and physical closeness may be marked by the development of strong emotional associations such as love or enmity. The sibling bond is often complicated and is influenced by factors such as parental treatment, birth order, personality, and people and experiences outside the family.

Types of siblings

Full sibling

A full sibling, is a sibling that shares both parents. Outside a case of identical multiples (such as identical twins or triplets), biological siblings will, on average, share 50% of their DNA since each will receive half of each parent's set of chromosomes. However, by chance distribution of the chromosomes, they could share as high as 100% or as low as 0%, but those scenarios are extremely unlikely.

3/4 sibling

A 3/4 sibling, is a sibling with one shared parent, and the other two parents are full siblings, for example if a man sires children with two sisters. This term is more commonly used in animal breeding.

Half sibling

A half sibling (half brother or half sister) is a sibling with one shared biological parent. A half sibling that shares the same mother (but different fathers) is known as a uterine sibling, whereas one that shares the same father is known as an agnate sibling. In law, the term consanguine is used in place of agnate. Half siblings can have a wide variety of interpersonal relationships, from a bond as close as any full siblings, to total strangers.

At law (and especially inheritance law) half siblings were often accorded unequal treatment. Old English common law at one time incorporated inequalities into the laws of intestate succession, with half siblings taking only half as much property of their intestate siblings' estates as other siblings of full-blood. Unequal treatment of this type has been wholly abolished in England and throughout the United States.

Quarter sibling

A quarter sibling is a half sibling's half sibling through their other parent. For example, Alice and Bill are half siblings who have the same father. Bill also has another half sibling, Carol, with whom he shares the same mother. Alice and Carol are "quarter siblings".

The term "quarter sibling" does not describe the genetic relationship between such siblings – while half siblings are half as related to each other as full siblings, quarter siblings are not genetically related to each other at all (unless they are related in a different, unrelated way). Instead of being based in genetic relatedness, it is based on an equivocation in which the use of the word "of" within mathematics to mean multiplication is applied to the idea of a "half sibling of one's half sibling" to conclude that a half sibling multiplied by a half sibling equals a quarter sibling.

While technically a mathematical fallacy, this term is not meant to imply a genetic relationship which does not actually exist. Rather, it is used as a colloquial term for a social relationship which would otherwise require an excessively wordy descriptor such as "half sibling's other half sibling through their other parent".

Stepsibling

A stepsibling (stepbrother or stepsister) is a sibling with whom a person bears no blood or adoptive relation, and is related by the marriage or relationship of one parent of the person to one parent of the sibling.

See also: stepfamily

Milk sibling

Milk brothers or sisters are children breastfed by a woman other than their biological mother, a practice known as wetnursing and once widespread in the developed world, as it still is in parts of the developing world.

In Islam those who are fed in this way become siblings to the biological children of their wetnurse, provided that they are less than two years old. Islamic law (shariah) codifies the relationship between these people, and certain specified relatives, as rada; once they are adult, they are mahram, meaning that they are not allowed to marry each other, and the rules of modesty known as hijab are relaxed, as with other family members.

Irish twins

"Irish twins" and "Vatican twins" are slang terms for siblings who are not actually twins, but rather, were born fewer than 12 months apart —possibly in the same calendar year and/or school year. It refers to the perception that Irish Catholic families have many children, often with little time between births. It is sometimes considered derogatory. Similarly, "Irish triplets" refers to three siblings born within a three year time period.

Godsiblings

A Godsibling (Godbrother or Godsister) is determined when one child is a Godchild of another child's parents. For example, if a child has a Godparent, and that Godparent has a child of his/her own, the child of the Godparent and the Godchild are Godsiblings. Godsiblings can either be related or non-related to each other.

Foster siblings

Foster siblings are children who are raised in the same foster home, or are also foster children of the person's parents, or foster parents' biological children.

Birth order

Main article: Birth order

The Benzon Daughters by Peder Severin Krøyer.

Birth order is a person's rank by age among his or her siblings. Typically, researchers classify siblings as “eldest”, “middle child”, and “youngest” or simply distinguish between “firstborn” and “later born” children.

Birth order is commonly believed in pop psychology and popular culture to have a profound and lasting effect on psychological development and personality. For example, firstborns are seen as conservative and high achieving, middle children as natural mediators, and youngest children as charming and outgoing. In his book Born to Rebel, Frank Sulloway argues that firstborns are more conscientious, more socially dominant, less agreeable, and less open to new ideas compared to laterborns. Literature reviews that have examined many studies and attempted to control for confounding variables tend to find minimal effects for birth order on personality. In her review of the scientific literature, Judith Rich Harris suggests that birth order effects may exist within the context of the family of origin, but that they are not enduring aspects of personality.

Some research has found that firstborn children have slightly higher IQs on average than later born children. However, other research finds no such effect.

In practice, systematic birth order research is a challenge because it is difficult to control for all of the variables that are statistically related to birth order. For example, large families are generally lower in socioeconomic status than small families, so third born children are more likely than firstborn children to come from poorer families. Spacing of children, parenting style, and gender are additional variables to consider.

Regressive behavior at the birth of a new sibling

The arrival of a new baby is especially stressful for firstborns and for siblings between 3 and 5 years old. Regressive behavior and aggressive behavior, such as handling the baby roughly, can also occur. All of these symptoms are considered to be typical and developmentally appropriate for children between the ages of 3-5. While some can be prevented, the remainder can be improved within a few months. Regressive behavior may include demand for a bottle, thumb sucking, requests to wear diapers (even if toilet-trained), or requests to carry a security blanket.

Regressive behaviors are the child’s way of demanding the parents’ love and attention.

The American Academy of Pediatrics suggests that instead of protesting or telling children to act their age, parents should simply grant their requests without becoming upset. The affected children will soon return to their normal routine when they realize that they now have just as important a place in the family as the new sibling. Most of the behaviors can be improved within a few months.

The University of Michigan Health System advises that most occurrences of regressive behavior are mild and to be expected; however, it recommends parents to contact a pediatrician or child psychologist if the older child tries to hurt the baby, if regressive behavior does not improve within 2 or 3 months, or if the parents have other questions or concerns.

Sibling rivalry

Main article: Sibling rivalry

Portrait of Lady Cockburn and her Three Eldest Sons , by Joshua Reynolds.

Sibling rivalry is a type of competition or animosity among brothers and sisters. It appears to be particularly intense when children are very close in age and of the same gender. Sibling rivalry can involve aggression; however, it is not the same as sibling abuse where one child victimizes another.

Sibling rivalry usually starts right after, or before, the arrival of the second child. While siblings will still love each other, it is not uncommon for them to bicker and be malicious to each other. Children are sensitive from the age of one year to differences in parental treatment and by three years they have a sophisticated grasp of family rules and can evaluate themselves in relation to their siblings. Sibling rivalry often continues throughout childhood and can be very frustrating and stressful to parents. One study found that the age group 10 to 15 reported the highest level of competition between siblings Sibling rivalry can continue into adulthood and sibling relationships can change dramatically over the years. Approximately one-third of adults describe their relationship with siblings as rivalrous or distant. However, rivalry often lessens over time and at least 80 percent of siblings over age 60 enjoy close ties.

Each child in a family competes to define who they are as persons and want to show that they are separate from their siblings. Sibling rivalry increases when children feel they are getting unequal amounts of their parents’ attention, where there is stress in the parents’ and children’s lives, and where fighting is accepted by the family as a way to resolve conflicts. Sigmund Freud saw the sibling relationship as an extension of the Oedipus complex, where brothers were in competition for their mother's attention and sisters for their father's. Evolutionary psychologists explain sibling rivalry in terms of parental investment and kin selection: a parent is inclined to spread resources equally among all children in the family, but a child wants most of the resources for him or herself.

Westermarck effect and its opposite

Anthropologist Edvard Westermarck found that children who are brought up together as siblings are desensitized to form sexual attraction to one another later in life. This is known as the Westermarck Effect. It can be seen in biological and adoptive families, but also in other situations where children are brought up in close contact, such as the Israeli kibbutz system and the Chinese Shim-pua marriage.

The opposite phenomenon, when relatives do fall in love, is known as genetic sexual attraction. This can occur between siblings brought up apart from each other, for example, adoptees who are re-united in adulthood.

See also

• Cousin
• Siblicide

Sister project links

Quotations related to Siblings at Wikiquote Media related to Brothers at Wikimedia Commons Media related to Sisters at Wikimedia Commons The dictionary definition of sibling at Wiktionary

• Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press. {{cite encyclopedia}}: Missing or empty |title= (help)