Discussing the age differences between himself and his siblings, Duhamel reflected on the birth of his youngest sister, Cassidy, who was born while he was in college.
“Cassidy came along, and I was playing football at Minot State University. I remember looking up at the stands, and I saw my mom and had this bump,” Duhamel shared. “And I’m like, ‘Is my mom pregnant?’ I’m 21 years old, and she’s having another baby.”
It wasn’t until recently that Duhamel noticed the surprising connection between his sister’s age and Mari’s.
“There’s a picture of me holding Cassidy as a 21-year-old young man with this little bitty infant,” he continued. “I looked at the photo, and I looked at my wife, and I said, ‘You and Cassidy are exactly the same age.'”
Lisa OConnor/AFF-USA.com / MEGA
“I am officially too old for you,” Duhamel jokingly quipped. “They’re literally like months apart in age. I never looked at it like that until I saw that photo. I was like, ‘Wait a second.'”
Duhamel, who tied the knot with Mari in 2022, shares two children with the beauty pageant titleholder and model: son Shepherd, 2, and daughter Rocca, 2 months. Before his marriage to Mari, Duhamel was famously married to singer Fergie, 51, with whom he shares 13-year-old son Axl. The pair split in 2017 and finalized their divorce in 2019.
The Ransom Canyon star previously discussed his age gap with Mari during a May 2025 episode of Not Skinny But Not Fat, telling host Amanda Hirsch that their age difference initially kept them from being a couple.
“It was truly platonic for years before that because I was like, ‘No, she’s too young for me. I’m not even going to go there,'” Duhamel said at the time. “Then, we started DMing back and forth.”
“Then, I invited her to a barbecue, still thinking it was totally platonic just as a friend from [North Dakota]. There aren’t many people from there. But she did come, and I saw her and I was like, ‘Holy [expletive] this girl’s beautiful.’ But then she’s more mature than I am,” he continued. “That’s really how we started dating, and it’s been a beautiful thing. We’ve been married now for over two years. She’s an amazing mother.”