Oh indeed, I don't think there's a shadowy cabal suppressing the knowledge of the existence of our third eye or anything like that. But in the past, the long arm of the catholic church certainly had a chilling effect on some research.

Like the guy who built some of the first microscopes and discovered the sperm in semen, he wrote to the scientific community to discuss the discovery, but made sure to include that the semen he used was "what was left" after he copulated with his wife. Wouldn't want to give anyone the idea that he had masturbated, heaven forfend!