It was not a real rule but kind of true.

First, the children of the king (legitimates and illegitimates but often legitimated) where present at Versailles. But they aged, married and had their own children. So it was all the descendants of the king (''les enfants de France'', the children of France) that where in the palace.

The majority of the people working in Versailles had small lodgings, where it was impractical to have your family. But some courtesan officers had their children with them, but didn't see them often: they were confined to appartements with their gooverness.

Often even the royal children where not formally presented before being 7 years old, which was deemed the age of reason, when boys became men and put on culottes instead of robe.

But at the end of Louis XIV reign we see some military officers enter the service early, we have mention of 14 y.o. lieutenants. François de Chevert, who would become general, entered service at 11! So it would not be impossible to find some of them in Versailles.

Sources:

• L'enfant et la famille sous l'Ancien Régime, Philippe Ariès

• Versailles: histoire, dictionnaire et anthologie, under the supervision of Mathieu da Vinha and Raphaël Masson

• Versailles, Vérités et légendes, Jean-François Solnon

• Versailles, Colin Jones

• Versailles, Tony Spawforth