brothers

Brothers are male siblings, defined as individuals who share at least one parent with another person. The term encompasses biological brothers (full siblings sharing both parents), half-brothers (sharing one parent), stepbrothers (connected through a parent's remarriage), and adoptive brothers (not biologically related but raised together as brothers).

Sibling relationships among brothers vary and are shaped by age differences, family structure, and parental guidance. Some brothers form close bonds through shared experiences; others experience rivalry or conflict. Brothers may assume protective, mentoring, or egalitarian roles within the family, and cultural expectations can influence their responsibilities toward younger siblings.

Etymology and culture: The word derives from Old English brōþor, related to other Germanic terms for brother. Beyond immediate family, "brotherhood" denotes solidarity among men in groups or communities. Cultural norms around brothers range from strong duties and loyalties to more voluntary, individual relationships that reflect family dynamics and personal history.

Genetically, full brothers share about 50 percent of their DNA. Legally, the status of brothers may affect inheritance rights or guardianship, and adoption or formal guardianship can establish or redefine brotherly relationships. Twin brothers are a subset of brothers; fraternal (dizygotic) twins are not genetically identical.