Tatiana and Krista Hogan are craniopagus twins (Tatiana is on the left). They are connected at the head and share a brain. They were born Oct. 25, 2006, to parents Felicia and Brendan Hogan of British Columbia, Canada. "These twins, I think to our current knowledge, are the only ones that do have a common neurological connection," said Dr. Doug Cochrane, the twins' pediatric neurologist. (Courtesy Renegade Pictures)