Euthitimos and Dionysadharos

Dionysadharos asked Euthitimos if he was the brother of his friend. The other replied that they were not brothers, but had a half-brother called petroclus. Dionysadharo then told him about Heracles' nephew and father's name: Ifacles. He also said Chairadimos wasn't his father; can a father be other than a father or are you same as a stone?