On very rare occasions, the opposite can occur, when twins are born with conjoint skulls. In a recent case, there is credible evidence of two young girls whose brains are connected at the level of their thalami. Each appears to have access to what the other one sees. If true, this would be a remarkable comingling of brains and minds, far above and beyond the ecstatic celebration of orgasmic dissolution of Tristan’s and Isolde’s identities in Wagner’s eponymous opera.
