Very generally speaking, in ancient Greece and Rome, daughters of free families usually left their parents' household and entered their husband's household when they married. Sons most often stayed in the household until their father's death and shared in the inheritance after he died. Sons did sometimes leave the household for various reasons and strike out on their own, but the age at which they did this varied considerably.

Although many households surely deviated from the norm, the stereotypical, normative household in both Greece and Rome consisted of the patriarch (the oldest living adult man, who had absolute authority over everyone else in the household), the patriarch's wife, all the patriarch's unmarried daughters, all the patriarch's sons (including both any child and adult sons he might have), all his adult sons' wives, all his adult sons' offspring, all the patriarch's slaves, and all the patriarch's adult sons' slaves.

I will start out by discussing when daughters left the home, because this was far more regular. Parents typically forced their daughters to marry when they were in their mid-to-late teenaged years. Men usually married much older, when they were in their late twenties or even their thirties. Consequently, it was the norm for teenaged girls to be married off to adult men more than twice their age.

The Athenian writer Xenophon (lived c. 430 – c. 354 BCE) wrote a dialogue titled Oikonomikos, in which one of the characters is an older gentleman farmer named Ischomachos who has a young wife. Ischomachos says in the Oikonomikos 7.5 that he married his wife when she was "not yet fifteen years old," which seems to be on the younger end of when girls usually married. Writing a generation after Xenophon, the Greek philosopher Aristotle of Stageira (lived 384 – 322 BCE) says in his Politics 7.1335a that the ideal age for a woman to marry is when she is eighteen years old and the ideal age for a man to marry is when he is thirty-seven.

Although it was probably rare for Greek or Roman girls to be married off when they were younger than fourteen or fifteen, it was certainly not unheard of. Notoriously, the Roman politician and orator Cicero (lived 106 – 43 BCE) married his former ward and second wife Publilia in either 46 or 45 BCE at a time when he was sixty or sixty-one and she was probably twelve or thirteen. (The marriage only lasted for a year and Cicero probably only arranged it in the first place because he desperately needed the money from Publilia's dowry in order to pay back the dowry for his first wife Terentia.)

In Athens during the Classical Period, women could not legally own real property in their own names. Consequently, an Athenian woman always had to be living in a household ruled by a man at all times. If, at the time of a patriarch's death, he had only daughters and no sons, then his daughter (or one of his daughters if he had more than one) was required to marry her closest living male relative (generally her uncle or cousin), so that he could inherit her father's property through her and thereby keep the property in the family. Even if the daughter was already married, she was required to divorce her husband to marry her closest living male relative. A woman who was the heiress to her father's estate and who was required to marry her closest male relative was known as an ἐπίκληρος (epíklēros).

In Sparta, some other Greek city-states, and Rome, by contrast, women could legally inherit and own real property in their own names if there were no male heirs. (Aristotle rather famously expresses his dismay in his Politics 2.1270a at just how much of the land in Sparta was owned by women.)

Now let's move on from the daughters to the sons. Upon the patriarch's death, if he had only one living son, that son would typically inherit all his father's property and his position as the patriarch of the household. As such, only sons and eldest sons usually stayed in the household until their father's death, unless there was some major falling out for some reason between the father and his son.

In neither Greece nor Rome was ordinary property inheritance usually determined by primogeniture. If the patriarch had more than one son, then younger sons could and frequently did inherit portions of their father's property. As a result, there was not nearly as much pressure for younger sons to leave the household and seek a living elsewhere as there was, for instance, in medieval western Europe. It was probably fairly common for younger sons to stay in their father's household for at least as long as he was still alive and share in the inheritance of his estate after his death.

On the other hand, many sons probably did leave their father's household and strike out on their own for various reasons. For instance, throughout the Archaic and Classical Periods of Greek history, Greeks were more-or-less continuously founding and growing colonies throughout the Mediterranean world. Many young Greek men left their homes to join these colonies. Many also left their homes to fight as mercenaries abroad, such as the famous "Ten Thousand" of Kyros the Younger, whose journeys through the Achaemenid Empire Xenophon chronicles in his Anabasis.

In the Hellenistic Era, the Greek monarchs of Hellenistic kingdoms were continually in need of Greek-speaking soldiers to serve in their armies, Greek-speaking administrators to staff their bureaucracies, and Greek people in general to inhabit their cities. As such, vast numbers of young Greek men left their homes to serve in the armies of and/or settle in the kingdoms of Ptolemaic Egypt and Seleukid Syria.

In the Roman Republic and Empire, many young Roman men left their homes to settle in Rome's colonies and provinces and, after the Roman army became professionalized in the late second century BCE, serve in the Roman army.