How much does genetics play in body shape/weight?

Muscles: We are born with anywhere between 40-60% of fast or slow twitch fibers. (strength or endurance) This can and will effect the ability to do well in either strength or endurance. Although it may be more difficult, you can train for either area.

Fat: We CAN be born fat depending on the quality and quantity of food consumed by the mother during pregnancy. However, this fat is easily lost. It won't affect genetics. Genes can influence the amount initial fat storing cells allowing for great initial fat stores. But, a cell can only store so much fat. If you put yourself on a calorie surplus, your body will make new fat storing cells. Even if you do have more fat storing cells at birth, it's only affects the ability to store fat. You can still burn the fat on a calorie deficit.

Bone structure: Very simple. Some of us have broader shoulders. Some have smaller hips, longer legs etc etc. Bone structure is the reason why people fail when they decide to look like a certain celebrity. Just look in the mirror and visualise the muscle. Isolate it in your mind and think about how the shape will change with increased size. Do strength/endurance training for that muscle to increase size. At the end of each workout, look at yourself to track your visual gains.

Bosy shape is100% genetics. You can't change your basic body shape unless you undergo some sort of surgical procedure. It all depends on the structure of your bones, and where your body decides to store fat.

Nobody is born fat i guess. If a person has a tendency to gain weight, though, it can be completely managed with diet and exercise (unless it is a thyroid problem or something).

In short, body shape you cannot change; body fat, you can.

You're not born fat, you're born with a genetic predisposition to gain weight in certain ways if your diet and lifestyle allow. Such people would need to be sporty and enjoy exercise and a good, varied diet to achieve a lean body. I.e. yes, it is harder for some people to sculpt their body or maintain their desired shape.

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id say 40- 50%

but its not everything. its only your pre disposition an what your most likely to be

working out an diet is more important.. get on those

Not much