My husband has been lifting weights, and one of his peck muscles is bigger than the other one. I noticed someone had already asked this question and you said to use dumbells instead of a barbell but he's tried that and still no change. What can he do to even them out. Is there any way you could be a little more specific. Thanks.

What sort of size difference are you talking about? I doubt it's extremely noticeable. Dumbbells are a good way to solve imbalances and it may just take more time. Genetics can also be a factor.