When we watch a bodybuilding video on utube about Arnold for instance , we often see in the comments someone just saying:"genetics", then someone saying "hard work", and finally someone saying "combination of good genetics and hard work".
I'm not saying that good genetics aren't important. We're made of what's encoded in our DNA. Of course it is important, but once we're created, what's done is done. Only Diet and Exercise can make a difference between 2 identical twins. We're not all twins in the population, but we're very similar overall.
The workout program defines the body. The genetics defines the limits. Thing is, very rare are the people who reach their potential limits, so genetics are not so important. Of course, good genetics can help achieve a certain goal easier and faster, with less effort. Still, it's the exercises and nutrition that will build this physique. I'm not talking about details. The encrypted code in your DNA will define how your skin look like, muscles, etc. But most people have a similar code.
Let's make an analogy with building a body and building a house. Arnold was saying he saw himself as an artist creating a sculpture, putting some clay here and there to shaphe the muscles the way he wanted them.
The DNA is the first architect of the body, or the foundation of the house, the nature of the soil on which it is built.
The workout program, the dumbells and weight machines are the tools (hammer).
The foods are the materials (nails, clay, etc).
All DNA are different for each person. Usually with just small differences. An infinite numbers of small differences, that are not so important when it comes to desigh the perfect workout routine. There's different ideal workout plan for different goals, different disciplines or sports, or for different body types. When I mean body types, I mean male/female, or very small versus very tall, etc. But the workout of Mr. America may be perfect for most bodybuilders too.
The shitty houses, it's not necessarily because of the architect, it may be because of poor materials(foods, weights) or workers (the bodybuilder).
Genetics are rarely to blame or the opposite. We've found a person with a gene that makes him immune to AIDS, but he's the only person discovered with this.
There's no identical DNA (except perfect twins), but we're all built around the same model, all coming from the same origin.
Most houses or cars are similar, because they're from the same models, with small differencies: the material used (foods for the body) and the quality of the workers (us).