For starters, it’s inconceivable that Rand Paul would be in the U.S. Senate—much less eyeing the White House—were it not for his father. He certainly would not have stood a chance in his 2010 Senate campaign when, as a new-to-politics ophthalmologist, he took on Mitch McConnell and the Kentucky GOP establishment, which was backing another primary candidate, Trey Grayson. The Paul name—and, perhaps more to the point, the grassroots fundraising network built up by Ron in his 2008 presidential campaign—provided “the rocket fuel” for Rand’s bid, says Rand’s former campaign manager David Adams. Without those, Adams adds, “Rand’s still checking eyeballs.”

Still, Rand is not merely continuing his father’s unfinished business; in his short career in electoral politics he’s made clear he’s a far more ambitious politician than Ron—and therefore a very different one. Not content to be merely a gadfly—as Ron was in the House and in his three presidential campaigns—Rand has tried to sand off some of the rougher edges of the Paul family’s libertarian ideology, especially when it comes to foreign policy. Where Ron was the only Republican to vote against a 2009 House resolution supporting Israel’s right to defend itself, for example, Rand took a much ballyhooed trip to the Jewish state earlier this year and has described his “kinship” with Israelis.