A very long time ago, I read Stephen King’s The Dark Half, where the protagonist had a tumor removed from his brain, which turned out to be his evil twin. This story is weirder.

The man above was feared to be carrying a gigantic tumor in his abdomen. When doctors opened him up, they found something more horrifying. An undeveloped fetus of his twin brother. I’m surprised the man was able to carry his brother for so long (36 years) without his body rejecting the fetus.

Source: ABC News