I don't see how that follows. Just because things can be explained by biochemical processes doesn't absolve anyone of responsibility. Even if you assume a person's behavior is completely deterministic, without any free will at all, holding someone responsible for their actions is still the right thing to do. It might change how we should treat those individuals, of course, but it isn't a get-out-of-jail-free card.

https://en.wikipedia.org/wiki/Moral_responsibility