A family is a socially recognized unit - typically connected by blood, marriage, cohabitation, or adoption - that provides emotional support and also functions as an economic unit within society.

Forms of kinship

In many societies, including the United States, people trace their lineage through both their father’s and mother’s sides. This pattern is called bilateral descent. Kinship refers to the relationships created through blood, marriage, or adoption, linking ancestors and descendants.

• Primary kinship involves the closest, most immediate ties, such as parents and children, spouses, or siblings.
• Secondary kinship extends one step beyond primary kin, such as grandparents and grandchildren, a sibling and their spouse, or a parent’s sibling (an aunt or uncle).
• Tertiary kinship includes more distant relatives, such as cousins, who represent third-degree connections.

Descent patterns

Cultures around the world define lineage in different ways. In roughly 60% of societies - especially highly industrialized nations - people use a bilateral descent system that includes both paternal and maternal lines. In about 40% of societies, which are common in pastoral regions, people use unilateral descent, tracing kinship through only one parent. Within these systems, there are distinct categories:

• in patrilineal descent, heritage and family names are passed exclusively through the father, reinforcing a sense of prestige associated with male lineage
• in matrilineal descent, maternal connections determine familial bonds and inheritance
• in ambilineal descent, the choice of lineage - paternal or maternal - depends on cultural preferences or situational factors.

Kinship systems

A society’s kinship system strongly shapes social relationships and how cultural values are passed on. Because kinship is defined through different forms of descent, it influences family structure and also helps determine rights, obligations, and social roles within a community. Whether a society uses bilateral or unilateral descent, these arrangements affect social support networks, how resources are allocated, and how traditions are maintained.

Diversity in family forms

The nuclear family

• Traditionally, the nuclear family - married parents and their children - was treated as the central social unit. Over time, this structure has become less common as more household arrangements appear. For example, many families today are formed by unmarried partners living together, reflecting a broad trend toward cohabitation. Single-parent households have also increased. In some situations, children are raised by guardians who are not their biological or adoptive parents due to various social challenges. These changes reflect shifts in kinship and in the overall organization of family life.

Marriage and divorce

• Social views of marriage have changed considerably. More couples choose to cohabit before marriage or instead of marrying, which contributes to a higher median age at marriage. The growth of same-sex unions, now legally recognized in many regions, also expands what marriage can look like in practice. At the same time, divorce rates have risen and fallen in response to changing laws and cultural attitudes, showing how long-term relationships are shaped by social conditions.

Divorce

• In 1960, the divorce rate was 0.9%. By 1975, it had more than doubled to 2.0%, peaking at 2.26% in 1980. Since then, rates have gradually declined to levels similar to the early 1970s. This change is partly linked to less rigid divorce laws and to women’s increased participation in the workforce, which has reshaped traditional social roles. Other factors - such as marrying at an older age and higher education levels - are also associated with greater marital stability. A declining marriage rate matters as well, since recent data show fewer new marriages per 1,000 people than in earlier decades.
• Regionally, the Northeast and Midwest tend to show lower divorce rates, while the South often shows higher rates, partly because people marry younger and marry more frequently. These are broad patterns, and there is still substantial variation within each region.
• Financial stress is a major contributor to marital breakdown. Couples without strong economic foundations - such as stable housing and savings - are much more likely to divorce within a few years. Research also suggests that the transition to parenthood, especially with multiples, can create a high-strain period. Over time, a gradual decline in marital satisfaction - often tied to changing personal values and life goals - can further increase the likelihood of divorce.

Conflict and violence in the family

Conflict theory argues that family life is not always a safe haven; it can also be a setting for power struggles. From this view, the way people carry out family status roles reflects how power and resources are distributed. Early research on marital power found that the person with greater access to valued resources - often through employment outside the home - tends to have more influence. Historically, this pattern often gave men more authority in many households.

Domestic violence is a serious problem in family settings, especially between spouses. To include violence involving unmarried, cohabiting, and same-sex partners, researchers often use the term intimate partner violence (IPV). IPV includes a range of abusive behaviors - physical, sexual, and emotional harm, as well as stalking and technological aggression. It may begin with subtle emotional mistreatment and escalate over time.

Studies suggest IPV is more common in some demographic groups. For example, Native American and Alaskan Native women experience higher rates than many other populations. Research also indicates that Black women experience higher rates of IPV than White women. Exact statistics are difficult to determine, in part because nonfatal IPV is often underreported.

Child abuse

Child abuse is a major social problem affecting millions of children. In recent years, more than 3.3 million reports were filed, involving roughly 5.9 million children. Many reports come from professionals such as teachers, law enforcement officers, and social service workers. Others are made by family members, neighbors, and anonymous reporters.

Child abuse takes several forms. The most common is neglect, meaning a failure to provide essential care, and it accounts for about 78.3% of cases. Other forms include physical harm (around 10.8%), sexual abuse (7.6%), and psychological maltreatment (7.6%). Some cases involve inadequate medical care (2.4%) or a combination of types. In most cases, parents are the perpetrators, with a smaller share involving other relatives.

Infants - especially those under one year old - face the highest risk, with an incidence rate of 2.6%. Because infants depend completely on caregivers, they are particularly vulnerable to neglect. The seriousness of this issue is often intensified by factors such as cultural values, differences in community standards of care, and widespread poverty.