It's pretty much their environment and what they're eating. I hunted a ranch in Central California that grows thousands of acres of barley. The hogs (the rancher calls them "Barley Sharks") bed down in the brush during the day and eat 'till gorged at night. Even the 350 lb boars taste outstanding. The meat is about the color of rose' wine and it's the closest I've seen to commercial pork. Then I've had 100 lb sows that have been eating "pookie" (term of art) that taste that way!