this is a good discussion that can go 100 pages.... my view based on what i've read, seen, and experienced first hand is if you look at studies done on humans, genetics, homeostasis, etc. we see a pattern that yes genetics does play a role in how you will look. also homeostasis is big.. this is why someone who has been fat for 15 years will do a calorie deficit diet, lose a few pounds, then just go back to their normal weight over time.
you can change your body structure, but it takes A LOT to do it. example is I will skinny all my life.. i changed my body by a lot of weight training consistently and taking a lot of shit.. steroids/supps/sarm's and eating more. i got bigger that way. if i see relatives today who hadn't seen me since i was 15 they would be shocked.. i was 112 pounds at that time skin and bones. the flip side is those 'jocks' from high school who were playing football have great genetics, but i bet most of them today are just fat 40 year olds cause they don't work out and they eat shitty. if they even tried to workout and eat good they would easily get ripped.
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