(Need Body-Builders to answer)My Arms are different?

OK, my Arms are different in their own ways. First, My RIGHT Arm has bigger Biceps, and opposing it my LEFT Arm has bigger Triceps. Now, I never treat them differently, nor do I change the amount of weights each Arm(or Hand) holds. They both hold the same weight(50lbs), and do the same exercises(an Example would be Bicep/Tricep extensions, and Skull Crushers). So what could be the problem?