I’ve always wondered if such a thing was possible. Apparently, it is. From Gizmodo:
This is one of the most surprising and awesome tales ever told in the
history of medicine. These twins are Tatiana and Krista Hogan. Their
brains and sensory systems are networked together, but they have
separate personalities. Their story defies belief.So much, in fact, that Tatiana and Krista Hogan shouldn’t be alive at
all. Their chances of surviving the pregnancy, birth and first months
of life were almost zero. Surprisingly, they turned four on October 25,
and they are still healthy and happy, as you can see in the photo above.They play Nintendo Wii games against each other, they fight for toys
and they share food and physiological functions. But they also share
their senses. For example, one can pick an object out of her field of
view, while the twin looks at the object.
Most importantly, however, they can share thoughts.
Check out the fascinating full article, replete with video and photographs, here.