Patrilineality

Patrilineality, also known as the male line, the spear side or agnatic kinship, is a common kinship system in which an individual's family membership derives from and is recorded through their father's lineage. It generally involves the inheritance of property, rights, names, or titles by persons related through male kin. This is sometimes distinguished from cognate kinship, through the mother's lineage, also called the spindle side or the distaff side.

A patriline ("father line") is a person's father, and additional ancestors, as traced only through males.

In the Bible
In the Bible, family and tribal membership appears to be transmitted through the father. For example, a person is considered to be a priest or Levite, if his father is a priest or Levite, and the members of all the Twelve Tribes are called Israelites because their father is Israel (Jacob).

In the first lines of the New Testament, the descent of Jesus Christ from King David is counted through the male lineage.

Agnatic succession
Patrilineal or agnatic succession gives priority to or restricts inheritance of a throne or fief to male heirs descended from the original title holder through males only. Traditionally, agnatic succession is applied in determining the names and membership of European dynasties. The prevalent forms of dynastic succession in Europe, Asia and parts of Africa were male-preference primogeniture, agnatic primogeniture, or agnatic seniority until after World War II. The agnatic succession model, also known as Salic law, meant the total exclusion of women as hereditary monarchs and restricted succession to thrones and inheritance of fiefs or land to men in parts of medieval and later Europe. This form of strict agnatic inheritance has been officially revoked in all extant European monarchies except the Principality of Liechtenstein.

By the 21st century, most ongoing European monarchies had replaced their traditional agnatic succession with absolute primogeniture, meaning that the first child born to a monarch inherits the throne, regardless of the child's sex.

Genetic genealogy
The fact that human Y-chromosome DNA (Y-DNA) is paternally inherited enables patrilines and agnatic kinships of men to be traced through genetic analysis.

Y-chromosomal Adam (Y-MRCA) is the patrilineal most recent common ancestor from whom all Y-DNA in living men is descended. An identification of a very rare and previously unknown Y-chromosome variant in 2012 led researchers to estimate that Y-chromosomal Adam lived 338,000 years ago (237,000 to 581,000 years ago with 95% confidence), judging from molecular clock and genetic marker studies. Before this discovery, estimates of the date when Y-chromosomal Adam lived were much more recent, estimated to be tens of thousands of years.