Should I tell my friends whole family that he's a pedophile?

Back in 2013, I was talking to my friend on Facebook. I forgot how it came up, but he said that the youngest girl he ever dated was 11. I'm not sure if he dated her, when he was a minor himself, or if he was an adult. I told his mom (who he lives with) about a year ago, because he has a niece he is around often. I just told his sister today, or at least I messaged he on Facebook saying that I was concerned for her daughter. I haven't got a response yet. My question is, should I tell his dad too who he lives with? I've only talked to him once the whole 11 years I've known him, so I don't know. Should I tell him too?

Should I tell my friends whole family that he's a pedophile?
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