Some sites say that Sam shares a young daughter with MacKenzie, but those rumors appear to be unfounded. In fact, you can apparently find similar unfounded rumors over on Tumblr, where some fans who ship Sam with his Outlander co-star Caitriona Balfe believe he has some secret kids with her. (Is this reminding anyone else of when Twilight fans said RPattz and KStew had a secret baby?)
In reality, all signs point to no wife or kids for Sam at the moment. For any fans who are hoping to change that — hey, shoot your shot!
Source: https://www.distractify.com/p/sam-heughan-kids