"Yeah, Kate and I have talked about kids... I want kids pretty soon. I don't want to be an old dad. My dad was pretty old when he had me, so I want to be able to run around with the kids and have a good time," Luke shared.
"I think when I brought it up with Kate, she was like, 'Oh!'"
Luke said Kate seemed to realize in that moment his plan for starting a family was "kind of soon" and she wasn't ready for that.
"It hadn't clicked with her yet that married people have babies right away or, like, soon. She's definitely more down the road. She's on, like, the five or six-year plan, maybe a little longer," Luke admitted.
Luke's Married at First Sight co-star, Keith Dewar, was then shown opening his eyes wide in shock on Unfiltered -- a reaction which prompted Luke to say with disappointment, "Yeah."
"So I was a little more into it -- a little more gung-ho," Luke concluded.
"You seem pretty ready for kids," Jamie told Keith on Unfiltered, trying to clarify his stance on welcoming little ones.
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"Yeah! I'm ready," Keith replied enthusiastically.
"But Kristine says, 'Look, let's get everything situated and squared away before we have kids.' She wants me to have a degree, muscles, I'm telling you! I got to [get rid of the keg], go to cooking school -- I've got a lot to do here, man!"
Keith, who was 29 years old when filming for Married at First Sight commenced, said he envisioned having children at age 28 or 30 his whole life.
"I'm over that hump!" Keith noted.
Jamie then asked Keith if the couple's completely different timelines for starting a family concerned him several weeks into his marriage.
"You know, I'm fine with that. We just got married. We married strangers. It's not like we've known each other for a few years and said, 'Alright, it's time to have kids.' But I'm glad she was open and honest about it, like, 'Nope, I'm not having kids right now,'" Keith told Jamie.