A Michigan couple welcomed their 12th baby boy to the family on Sunday, August 4. They were hoping for a baby girl for once in the 11 pregnancies, but say that they feel blessed to have a healthy 7-lb., 12-oz. newborn. Tucker Ryan was held in his mother’s arms as FOX News interviewed the bunch, with the occasional running toddler and smiling young men.

The couple, Jay and Kateri Schwandt, were confident that the 12th surprise pregnancy would break the gender streak and give them a girl, but as she approached nine days past her due date, they laughed when they found out it was another boy.

“Of course. There was a chuckle in the whole room,” Kateri, 38, told the Associated Press on Thursday when Tucker arrived at the Grand Rapids hospital. “I looked at my husband and we exchanged a knowing smile. When they say it’s a boy, I think, OK, no problem. I’ve got this. We know what we’re doing.”

The Schwandt family does know what they're doing, as they survive off of a help-out system, in which the older boys take care of the little guys and even know very well how to change diapers. By the time they reach sixth grade, it’s a known passage into responsibility when they learn to take care of their own laundry.

“I’m sure a little girl probably would be fun, but we know what we’re doing. Sometimes I feel like I’m living in a locker room,” Kateri told FOX affiliate WXMI. She said that the family “operates on flow charts and chores, sports and Band-Aids.”

Kateri will stay at home with three of the boys, including her new bouncing baby, while five are in elementary and middle school, three are in high school, and her oldest son Tyler is 21 years old and always happy to help, she says.

The family lives north of Grand Rapids and considers themselves stringent Roman Catholics who follow the bible’s teachings of no birth control. Kateri comes from a family of 14 children herself, and even her sister, Kate Osberger, has 10 children of her own who are also all boys.

“That’s amazing. This is a miracle,” Dr. Bob Barbieri, a fertility researcher and chairman of obstetrics and gynecology at Brigham and Women’s Hospital in Boston, told FOX News. “It appears there is some type of genetic determination in some families that have a lot of girls or a lot of boys. It’s not well understood. It’s more of a statistical oddity.”

What are the odds, then, of a family having all those boys? According to Jay, the chances that he would father 12 consecutive boys were extremely slim. There is a 50 percent chance that your first child will be the same gender as your second child; however, the third child only has a 25 percent chance at being the same gender as his or her two older siblings. It continues down the line with split odds; there is a 12.5 percent chance for the fourth child, a six percent chance for the fifth child, and a three percent chance for the sixth child. By the time the Schwandt’s reached their 12th child, there was a .005 percent chance that it was going to be another boy.

“It’s like flipping a coin 12 times and every time it comes up heads. It’s pretty rare but it’s happened,” said Jay.