I have a possible theory of why pecs become uneven?

I notice that a lot of people have uneven pecs when they work out and I have a theory. Since we know there is no workout that focuses strictly on pecs, because you also use your arms. I think that since all the people I know that are right handed have bigger left pecs I think that since your right arm is stronger than your left it can support more weight, therefore the pec on the side of your weaker arm gets more of a workout because more weight is focused on that pec, anyone following me?