Q.: "Is it posible for conjoined twins to be conjoined head to leg or arm to back? Basically, not having the same parts conjoined?"
Conjoined twins are a type of monozygotic twins; they develop from a single fertilized egg that splits into two. In the case of conjoined twins, the split occurs later – more than 8 days after conception – and does not completely separate, leaving the zygotes connected. Because of the way the cells develop symetrically, conjoined twins will be attached by a corresponding body part – head to head, chest to chest, anterior to anterior. (For a listing of the types of connection, see the Conjoined Twins FAQ.
So, the short answer to your question is: No.
Conjoined twins, also known as Siamese twins, are a rare type of monozygotic (identical) twins. Find more answers to Frequently Asked Questions About Conjoined Twins. (If you have a question that is not answered here, please e-mail me: multiples.guide@about.com.)
