Alexa Ray Joel and Christie Brinkley

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Billy was once married to supermodel Christie Brinkley, and they have a daughter together, 22-year-old Alexa Ray. Billy says he and Christie have maintained a good relationship. "We made a point of getting along for her sake," he says. "It's real important."

Although Alexa Ray is following in her father's footsteps as a musician, Billy says she's making it on her own. "I don't push," he says. "I'm not a stage dad." If she calls, Billy says he'll give her advice—but only when she asks for it. "If she has a question about a chord change or a recording process or what's the next step in the music industry, I'll tell her my experience."