Sanju Bhagat's case has been described as a rare medical condition, Fetus in Fetu, also popularly known as the 'vanishing twin syndrome'. In this case, Bhagat's twin was reabsorbed by him, leading to one twin being literally born inside the other. Basically, the inside twin lives like a parasite but usually, the ‘host twin would realise something was happening – not ignoring it like Bhagat.