Genetics is one of those topics that tends to get used two very different ways in gym conversations. Some people use it as an excuse for why they're not further along, others insist it barely matters at all if you just work hard enough. The truth sits somewhere in the middle, and understanding what genetics actually influences can save you a lot of frustration and help you focus your effort where it actually counts.

Muscle fibre type is one of the clearer genetic factors at play. Some people are naturally built with a higher proportion of fast twitch fibres, which tend to have greater growth potential, while others lean more toward slow twitch fibres suited to endurance. This is part of why two people can follow an identical program and end up with noticeably different results, since their muscle is responding to the same stimulus with a different underlying starting point. It's not something you can change through training, though it does explain a good chunk of why comparing yourself directly to someone else rarely tells you much useful.

Muscle insertion points, essentially where your tendons attach to bone, also shape how a muscle looks once it's developed, regardless of how hard you've trained it. Someone with a slightly longer bicep muscle belly will get a fuller looking arm at a similar level of development compared to someone with shorter insertions, purely because of the anatomy underneath. This has nothing to do with effort or consistency, it's just the shape you were dealt, and no amount of extra training volume will change where your tendons attach.

Hormonal factors, particularly natural testosterone levels, add another layer of individual variation. Within the normal range, people do vary somewhat in how much of this hormone they naturally produce, which can influence how readily they build muscle even with identical training and eating habits. This is genuinely outside your control, and it's a big part of why comparing your rate of progress to someone else's, especially online where you have no idea what you're actually looking at, is rarely a useful exercise.

What you can control matters just as much, if not more, in practice. Training consistency, how close to failure you actually push your sets, how much quality sleep you're getting, and whether your protein intake is genuinely dialled in through food and things like Whey Protein Isolate or EAAs are all factors entirely within your hands. Most people who feel like their genetics are holding them back haven't actually maximised these controllable factors yet, and there's usually a lot more progress available here than people assume before genetics becomes the real limiting factor.

The most useful way to think about genetics is as something that shapes your ceiling and your rate of progress, not something that decides whether progress happens at all. Everyone with reasonably functioning biology can build meaningful muscle over time with consistent training, adequate protein, and enough recovery, even if the exact pace and final shape differs from person to person. Rather than treating genetics as a reason to hold back, it's more useful to treat it as the backdrop you're working within, then focus your energy on the training, nutrition and recovery habits that actually move the needle for you specifically.