I was listening to the radio this am and this subject was discussed. They said that it happens in 1 in 1000 cases. I wish you luck in whatever you find out! My last child came when I was 36 and thought my baby years where long gone. I also had teenage children and was surprise how much they love each other. While they may never be close like other siblings, ( he is in Iraq and she is in the 2nd grade) they have such a special bond its amazing! Good luck!!