Some people in China (even a professional bodybuilding instructor who I met in the last gym I visited) think that there is something genetic (genetic advantage) when it comes to the white (Caucasian) people building muscles. Of course it's not true -- white, yellow, black, mixed -- all of us need hard work out + right food + right drinks when we want to build better bodies.
The incels in question who think that there are Chads who're with perfect bodies only because they have got good genes are wrong. They absolutize the genetics. The genetics is the base. When the base is better your bodybuilding will be also better but when there is only a base without bodybuilding or at least some serious sports activity then the result is fat or chubby body (at best -- an average body, when the diet consists of both healthy food and healthy drinks.)
Think about it -- did you ever met a Chad (Chang, Tyrone) who isn't playing American football, rugby... practicing wrestling, MMA, judo, karate, kick boxing... or at least, hitting the gym, doing yoga, running, biking...
The Chad from the meme above may have this kind of body only if he's not eating too much + if he's a regular swimmer (and adding some simple gym exercises at least 3 times a week). There are no people "just born like this".
The gymmaxed incel can't look like that if he's not a professional bodybuilder.