In Roman law, the power to give children in adoption was one of the recognised powers of the pater familias. The adopted boy would usually be the oldest, the one with proved health and abilities. Adoption was an expensive agreement for the childless family and quality must be insured. Adoption was agreed between families of equal status, often political allies and/or with blood connections. A sum of money was exchanged between the parties and the boy assumed the adoptive father's name, added by a cognomen that indicated his original family (see Roman naming convention). He also acquired the adoptive father's status, meaning that if the boy was born in a patrician family, he would become a plebeian through adoption, and vice versa. Adoption was not secretive or considered shameful, nor was the adopted boy expected to cut ties to his original family. Like a marriage contract, adoption was a way to reinforce inter-family ties and political alliances. The adopted was often in a privilege situation, enjoying both original and adoptive family connections. Almost every politically famous Roman family recurred to it.
Probably the most famous adopted man in Republican times was Augustus Caesar. Born as Gaius Octavius, he was adopted by his great-uncle Julius Caesar and acquired the name of Gaius Julius Caesar Octavianus. This is why Augustus is often mentioned in literature as Octavian.
In the Roman Empire, adoption was the most common way of acceding to the throne without use of force. During the 2nd century, in the Nervan-Antonian Dynasty, the most apt successor was adopted by the emperor, thus legalizing his position. Emperors like Trajan, Hadrian or Marcus Aurelius are examples of adopted successors. Another example of an adopted Roman Emperor is Nero. He was the son of Gnaeus Domitius Ahenobarbus and Agrippina Minor, a woman of the imperial family, and was named Lucius Domitius Ahenobarbus. In AD 49 his mother married Emperor Claudius and persuaded him to adopt Lucius as his son. He then acquired the name Tiberius Claudius Nero Domitianus and inherited the throne in AD 54 as Nero.
Adoption proved a more flexible and workable tool for orderly succession in the Roman Empire than natural succession did, seeing that it guaranteed that people of promise, and often of proven competence, were named as official successors to what was in effect a military dictatorship. By contrast, the succession of Marcus Aurelius's natural son Commodus to the throne proved to be a turning point in the Empire's declining fortunes.
See also: Roman culture