Esperanto as a native language, mother tongue, first language?

George is interviewed about his native language.

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George: My parents were Hungarian but my native language is Esperanto.

Interviewer: Esper-

George: Esperanto. Yes. It was the first language I learned. So I can say I am a native speaker of Esperanto.

Interviewer: Native.

George: In the sense that I am as proficient as a person who speaks nothing but Esperanto.

Interviewer: Are there any?

George: Well, I admit you’d be hard put to find anyone more than 3 or 4 years old who used anything but Esperanto. Some families start teaching their baby but they end up teaching more than one language.

Interviewer: Since it is a planned language, doesn’t belong to any country or area, it lacks a culture, wouldn’t you say?

George: Lacks a culture? There are speakers. You can stay with Esperanto speaking families.

Interviewer: But there is no Esperanto food, or clothing, or architecture, or furniture or tools, or music, or dances, or festivals… or… for me, a language springs from its culture. That’s what I’d call a native language. Society has natives. Plural. Your case is rather unique. Maybe you could call Esperanto your mother tongue. It did come from your mother.

George: It's not that simple. Mothers don't always teach their own language to kids. How about we say first language?

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