John Luke and Mary Kate Robertson aren’t just growing their family by one — but by two! “Absolutely thrilled to tell y’all we are welcoming TWINS to our family early next year,” the couple wrote in the caption. Related: How Exactly Is Willie Robertson Spending Retirement? The Robertson family was quick to express their excitement for the growing family in the comments. I am so proud of your little growing family and can’t wait to be a twin Kmama.”John Luke’s sister Sadie Robertson also chimed in.