Native Esperanto speakers
Native Esperanto speakers (Esperanto: denaskuloj [denasˈkuloi̯] or denaskaj esperantistoj [deˈnaskai̯ esperanˈtistoi̯]) are people who have acquired Esperanto as one of their native languages. As of 1996, there were 350 or so attested cases of families with native Esperanto speakers.
Source: Wikipedia — Native Esperanto speakers (CC BY-SA 4.0)