Cadet line

In history and heraldry, a cadet branch consists of the male-line descendants of a monarch or patriarch's younger sons (cadets). In the ruling dynasties and noble families of much of Europe and Asia, the family's major assets—realm, titles, fiefs, property and income—have historically been passed from a father to his firstborn son in what is known as primogeniture; younger sons—cadets—inherited less wealth and authority to pass to future generations of descendants.

In families and cultures in which this was not the custom or law, as in the feudal Holy Roman Empire, equal distribution of the family's holdings among male members was eventually apt to so fragment the inheritance as to render it too small to sustain the descendants at the socio-economic level of their forefather. Moreover, brothers and their descendants sometimes quarreled over their allocations, or even became estranged. While agnatic primogeniture became a common way of keeping the family's wealth intact and reducing familial disputes, it did so at the expense of younger sons and their descendants. Both before and after adoption of inheritance by primogeniture, younger brothers sometimes vied with older brothers to be chosen their father's heir or, after the choice was made, sought to usurp the elder's birthright (cf. Jacob and Esau).

In the parts of Europe where primogeniture prevailed, cadet sons were generally entitled to receive an appanage in patrimony, always substantially smaller than the eldest son's inheritance. Often, especially outside of Germany, the younger branch remained subordinate to the elder line as vassals or subjects.

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