Jax and Jett were born to two sets of identical twins.

Two identical twin sisters have left their followers in shock after revealing that their individual sons are cousins, brothers, and twins all at once. Briana and Brittany Sayler are known for starring on TLC's Extreme Sisters - a show about siblings who share close and fairly intense bonds with each other. The pair married two identical twin brothers and each couple welcomed baby boys within three months of each other - Jax and Jett. And the two baby boys are certainly unique. https://www.instagram.com/p/CVWDTDUvT1r/ Posting a cute photo of Jax and Jett to their shared Instagram page, the twin mums wrote: "Cousins, genetic brothers, and quaternary twins." Quaternary twins occur when two pairs of identical twins have children. In this case, the children, who would typically be considered first cousins, are also technically genetic siblings. Jax and Jett's DNA is the same as it would be if they were brothers. It all sounds pretty complicated, but one fan in the comments summed it up well: "Their mothers and fathers are identical twins. Both sets of parents then had kids. Same exact DNA created both. Make sense?" Another clarified: "Identical twins share the same DNA and both sets of parents are identical. If this family took an ancestry DNA Test it would show these babies as siblings, not cousins!” https://www.instagram.com/p/CYRkuIQrO7-/ Others took to the comments to say how adorable the special little boys are and how they look so alike. "Amazing how they really do look like twins, even with the age difference," one person said. "I thought it was the same baby at first!" another wrote. A third simply added: "Such handsome little boys." On Extreme Sisters, Briana and Brittany showed how they both live together with their two partners under one roof and raise their babies - together as one big family.