Comment by h2zizzle

Can sort of confirm. I wouldn't say so much "genetics" as "constitution". That is, you're born with a set of attributes, and those can also be affected by circumstances outside of your control. Those come together to determine how you respond to exercise and whether you can exercise consistently at all. Someone with active and athletic parents who was affected by undiagnosed childhood diseases and poorly managed injuries (*cough*) is going to have health and performance problems that keep them out of the gym. Someone who builds muscle very slowly but who can just keep at it for 10, 15 years is going to be jacked.

We also don't account for the role of money in these things. Do you make enough to buy good food, afford a decent gym that you can visit regularly, afford a good doctor who can help you manage issues (such as, ahem, low testosterone)?, afford a low-uncontrolled-stress lifestyle? You're good. It's a lot harder when you get hit by roadblocks and don't have the money to resolve them before you've detrained.