Taylor Hanson and Wife Natalie Expecting Sixth Child

Taylor Hanson‘s family is expanding — again!

The Hanson keyboardist and vocalist, 35, is expecting his sixth child with wife Natalie, he announced on Instagram Tuesday alongside a photo of their entire family: the parents-to-be with daughters Wilhelmina “Willa” Jane, 5?, and Penelope “Penny” Anne, 13, plus sons Viggo Moriah, 9?, River Samuel, 12 next month, and 15-year-old Jordan Ezra.

“What’s better than being a dad of five? Perhaps being a dad of six,” the longtime musician and budding photographer captioned the outdoor snapshot. “Baby Hanson coming in December and we are over the moon.”

He tells PEOPLE exclusively, “Natalie and I have always kept a love of adventure and pursuit of rich experiences at the heart of our family. There’s no greater adventure than welcoming a sixth little person to our tribe.”

Natalie posted another photo of their brood surrounded by musical instruments, captioning it, “Taylor and I are so thrilled to share the news that baby number six is coming this December! Ezra, Penny, River, Viggo and especially Wilhelmina can’t wait to be big brothers and sisters again!”

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RELATED GALLERY: MMM-Tots! Your Guide to The Ever-Growing Hanson Family Tree

The baby on the way joins an impressive lineup of cousins from Taylor’s brothers, Zac Hanson and Isaac Hanson. Zac and wife Kate welcomed their fourth child, daughter Mary Lucille Diana, in August 2016. She joined the couple’s daughter Junia Rose Ruth, 7?, plus sons George Abraham Walker, 4?, and John Ira Shepherd, 10.

Isaac and wife Nikki are parents of three: 4-year-old daughter Nina Odette plus sons James Monroe, 10, and Clarke Everett, 11, while the Hanson brothers themselves are the oldest three in a family of seven children.

Aside from Ezra, all of the adorable youngsters starred in the music video for the band’s 2017 hit “I Was Born,” which Taylor told PEOPLE was a decision based in getting the song’s core message out there.

“From the earliest conversations about this song, we imagined kids featured in the video to elevate the song’s message of unbridled optimism for the future,” he told PEOPLE exclusively.

RELATED VIDEO: Zac Hanson Welcomes Daughter Mary Lucille Diana

In a post on her blog, Natalie shared more photos from the shoot (including a sweet one where she’s cradling her baby bump!) and echoed her husband’s sentiments, writing, “Taylor and I and all the children are so excited about the new family member coming this December! More than ever I realize how time flies and every moment with these people counts.”

She also shared some details about the family’s dynamic as they hit the road this fall for Hanson’s String Theory tour, with a subsequent album being released later in the season.

“Because of the timing of these shows and everything going on with us, we decided now was a great time to stick together and do this as a family,” she wrote. “So, we are back on the road! It’s been a while since we’ve had the whole crew with us full time and it’s crazy to think how little they were in years past. Now we have these big kids who are so cool and fun and help out big time.”

“Being full time on the road means #roadschool is back in session and so far so good,” explained Natalie, who home-schools the couple’s children. “Once again our dynamics have shifted so much since everyone was small and even school feels like much more of a team effort. I look forward to sharing some of our journey with you all!”