AXS TV's series Music's Greatest Mysteries will explore the age-old question of who really invented the "horns" gesture in rock and metal. The new episode will air on July 14 and will touch on the origin of the gesture, as well as explore claims made by Ronnie James Dio, Gene Simmons, and Jinx Dawson about potentially inventing it.
Personally, I like to believe the Devil just came right up from hell one day and showed some random person. Though I'd imagine getting a hold of the Devil to ask a few questions might be difficult.