Witness the key moments during early embryogenesis from the spontaneous splitting of a single fertilized egg into identical twins through to the major milestones of twin fetal development, ending with their dramatic births.

Along the way, learn how skin color is formed; what happens when aberrations in early development occur, producing conjoined twins; and how twins with ambiguous genitalia (hermaphrodites) can develop. Meet a pair of identicals who were separated at birth and met for the first time four decades later. Then, see dramatic 4-D ultrasound images of twins interacting in the womb in real time.