The larger worm in the top image is a hermaphrodite -- a worm with male and female organs -- while the worm on the bottom is male. Biologists at the Brain Institute at the University of Utah genetically manipulated the brains of hermaphrodite worms so they were attracted to other worms of the same sex. The study showed sexual orientation is wired in the worms' brains. Credit: Jamie White, University of Utah University of Utah biologists genetically manipulated nematode worms so the animals were attracted to worms of the same sex – part of a study that shows sexual...