If it's all genetics then why are we seeing these smallmouth bass that look like they've swallowed a bowling ball, what seems like more frequently since the gobie came around? The world record hasn't been broken and to my knowledge is a pretty old record as well. But it seems like the addition of a new food source has changed things a bit in certain areas.
Another example is LaPerla ranch in Texas with Dr. Gary from Techomonte. He selected the fresh water lobster (I believe) to help these bass put on weight quicker. Obviously genetics and selective breeding, habitat and location (environment) play a role as well. Dr. Gary has made a name for himself producing some of the biggest bucks on the planet. He's done this by taking the biggest bucks (genetics) selectively breeding them, and by giving them the best minerals and feed (diet) and the best land with the least amount of pressure, stress, and predation possible (environment).
Again I don't argue that genetics plays a major role in fact I'll take a shot in the dark and say it plays well over 80%. I'm not a smart man but I have enough brain to know that without good genes you won't develop much. On the flip side you can have the best genes, but if you have a poor diet will little protein or fat chances dwindle for producing a world record bass. Just like if you take a lake (environment) that is over populated, not the best water, and many other factors you chances for producing a world record bass does it not?
Again I'm no expert and I'm going by what I've read over the years.