Agrippina was the first daughter and fourth living child of Agrippina the Elder and Germanicus. She had three elder brothers, Nero Caesar, Drusus Caesar and the future Emperor Caligula, and two younger sisters, Julia Drusilla and Julia Livilla. Agrippina's two elder brothers and her mother were victims of the intrigues of the Praetorian Prefect Lucius Aelius Sejanus.
She was the namesake of her mother. Agrippina the Elder was remembered as a modest and heroic matron, who was the second daughter and fourth child of Julia the Elder and the statesman Marcus Vipsanius Agrippa. The father of Julia the Elder was the Emperor Augustus, and Julia was his only natural child from his second marriage to Scribonia, who had close blood relations with Pompey the Great and Lucius Cornelius Sulla. Maternally, Agrippina descended directly from Augustus.
Germanicus, Agrippina's father, was a very popular general and politician. His mother was Antonia Minor and his father was the general Nero Claudius Drusus. He was Antonia Minor's first child. Germanicus had two younger siblings; a sister, named Livilla, and a brother, the future Emperor Claudius. Claudius was Agrippina's paternal uncle and third husband.
Antonia Minor was a daughter to Octavia the Younger by her second marriage to triumvir Mark Antony, and Octavia was the second eldest sister and full-blooded sister of Augustus. Germanicus' father, Drusus the Elder, was the second son of the Empress Livia Drusilla by her first marriage to praetor Tiberius Nero, and was the Emperor Tiberius's younger brother and Augustus's stepson. In the year 9, Augustus ordered and forced Tiberius to adopt Germanicus, who happened to be Tiberius's nephew, as his son and heir. Germanicus was a favorite of his great-uncle Augustus, who hoped that Germanicus would succeed his uncle Tiberius, who was Augustus's own adopted son and heir. This in turn meant that Tiberius was also Agrippina's adoptive grandfather in addition to her paternal great-uncle.