8 lbs. 4 oz.
When it comes to lullabies, 8-week-old Shepherd Hanson is one blessed baby. "He's heard a lot of original a capella dad—it's Zac Hanson: The Solo Project," says Zac Hanson, the youngest member of the rock trio Hanson. Luckily for Zac, 22, and his wife, Kate, 24, they won't have to navigate first-time parenthood alone. The new dad's brothers and bandmates Isaac, 27, and Taylor, 25, live nearby in the family's hometown of Tulsa with their wives and five young children between them. This Hanson baby boom has prompted one blog to refer to them as "breeding machines," but Zac brushes off such unflattering comments. "We only have one baby," he says. "What's all the drama?" Besides, having siblings who've already been through it eases any new-parent anxiety. "There's always someone to tell you, 'It's okay that the baby hasn't pooped, you don't need to worry about that,'" says Zac. "But we have no intention to battle the Osmonds in any way—they can have the crown!"
But Shepherd will get a taste of the Donny-and-Marie life when the entire Hanson clan piles onto the tour bus for the band's "Walk Around the World" tour in September. "I'm looking forward to taking him on adventures and doing fun kid things," says Kate. Correction, says the proud papa: "What she means is all those fun things that we want to do but need excuses," he says with a grin. "Legoland is already on the calendar!"
Video special: Go behind the scenes with the new family at PEOPLE.COM/HANSONBABY