This might be hard to under stand but bare with me.
So what would your first language be if
Your dad's from France his first language is French and his second language is English
Your mums from England her first language is English and her second language is French
You all live in idk Turkey but don't speak it only French and English
You speak both French and English at home the same amount 50 French /50 English.
What's your first language?
I asked someone they said both French and English would be your first language but I'm curious sorry if this hard to understand.