While it may be true that genes might play a role in the size of forearm muscles, they are not the be-all-end-all determinants of bigger forearm muscle growth. The right exercises can build massive forearm muscles.

Are skinny forearms genetic?

Also, it's possible that your skinny forearms are due to your genetics. ... While your genes certainly play a role in muscle size, a healthy, high protein diet coupled with enough resistance training can overcome most genetic deficits—small forearms included.

Why do some people have huge forearms?

But they're normal based on the reality that they grow from strength training like any other muscle group. Therefore, the main reason why you might wind up with forearms bigger than biceps is that you're simply training your lower arms harder and heavier than your upper arms.