It’s most probably genetics.

But if you mean like Ronnie Coleman, then it’s because of insulin and HGH overdose consumptions.

Or else it’s just your genes

Extra photo for clarification

(This is my first time writing on Medium; so I started by reposting my best answers from Quora; you can check me out there as well https://www.quora.com/profile/Habib-Merii/answers )

Thanks for reading, more better content is yet to come.

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