Donor Sibling Twins!!!
After I conceived my son through sperm donation I joined the registry to see if he had any siblings. I found out that he in fact did and when I contacted them we discovered not only were they half brothers but they shared the SAME birthday!
I cannot imagine that this happens to often. We have stayed in contact over the years and now that the boys are teenagers they have connected with each other through social media and they are getting to know each other. We hope to all meet face to face sometime in the near future.