In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.

Sentence1: Paul decided to find out about his birth parents. Sentence2: He asked his adoptive parents about them. Sentence3: They told him his mother had been a prostitute. Sentence4: Paul looked at them stunned. Sentence5: He decided not to ask them who his father had been.
Paul, Adoptive parents, Father, Birth parents, Mother