By Rennie Dyball

Originally posted Wednesday December 10, 2008 04:55 PM EST

Taylor Hanson and His Wife Welcome Baby No. 4 | Taylor Hanson
Make way for the newest Hanson!

Taylor, the middle brother of the rock trio Hanson, and his wife Natalie
welcomed a son, Viggo Moriah, on Tuesday in Tulsa, Okla., they tell PEOPLE
exclusively.

"Viggo is doing great. He is the perfect early Christmas gift," the couple says
of their 8 lb., 5 oz. arrival. "We look forward to being home to enjoy the
holidays with him and his very excited brothers and sister."

Viggo joins older brothers Ezra, 6, and River, 2, and sister Penelope, 3. The
growing Hanson family also includes their cousins, Isaac and Zac's kids,
Everett, 1, Shepherd, 6 months, and Monroe, 5 months.

Taylor, 25, and Natalie, 24, announced in August that they were expecting.

Taylor and his bandmate brothers recently released Take the Walk, a book chronicling
their experiences working to fight AIDS and poverty in Africa. They plan to get
back into the studio early next year and hope to release a new album by the
summer.