The latest member of the Schwandt family was born on Wednesday morning in Grand Rapids, Michigan.
In keeping with family tradition, Jay and Kateri Schwandt chose not to know the baby's sex before the birth.
"I was thinking, 'If this is a girl, I don't know what my reaction is going to be'," said Mr Schwandt, 40, just moments after his son was born.
The ages of their boys extend over more two decades, starting with Tyler, 22, followed by Zach, 19, Drew, 18, Brandon, 16, Tommy, 13, Vinnie, 12, Calvin, 10, Gabe, 8, Wesley, 6, Charlie, 5, Luke, 3, and 21-month-old Tucker.
"There's a lot of commotion, a lot of chaos, but there's also a lot of love," said Ms Schwandt.
The family is now trying to settle on yet another boy's name, and have been seeking a little help from their other sons.
But so far the boys still haven't agreed on a name.
Kateri Schwandt, 40, comes from a family of 14 children.
She was the 13th child born in her family and she says that the significance of the 13th child being born on the 13th day of the month has not been lost on them.
The Schwandt family has been approached by several TV production companies with offers of their own reality show, according to the Grand Rapids Press newspaper.
Mother and son are both doing well and resting in hospital.
But are they likely to add a 14th boy to the family in the future?
"You never say never," said Mr Schwandt.
