Tom Petty is a good ten years younger than Jagger et.al. He didn't leave Gainesville for the West Coast until the early 70's with Mudcrutch and didn't form the Heartbreakers til maybe two years later.
His family does tend toward the lean side tho. When he was a kid he had to stand in the same place twice to cast a shadow. He started out playing bass and I think it weighted more than he did.

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