From an epilogue of the play Peter Pan: The Boy Who Wouldn't Grow Up by J. M. Barrie, he writes that after Wendy returns to her real home, Peter comes to visit her years later.
Wendy has grown up and has a daughter of her own, who Peter takes to Neverland.
This happens again with Jane's daughter, Margaret.
How old is Peter Pan? When did he run away from his parents and become the first Lost Boy?