Which is the antecedent and the pronoun in this sentence Jack doesn't know John or where his sister lives?

"Jack doesn't know John or where his sister lives."

The pronoun is the possessive adjective 'his', but we don't know if it describes the sister of Jack or the sister of John. This is called an 'unclear pronoun antecedent reference'. In other Words, the antecedent can't be determined by the Wording of the sentence.