Emanuel Derman in his post 'To me you’re a wave, but to myself I’m sometimes a particle' compares moral behavior with the wave/particle duality in Quantum Mechanics. Just as behavior of matter can simultaneously be viewed as being a wave or a particle, he says that behavior of humans can simultaneously be viewed as having responsibility for their actions and as not having free will.
When I do something GOOD, I like to say I acted freely, and I experience it that way.
When I do something hurtful or BAD, I sometimes excuse myself by saying I couldn’t help it (meaning I experience the cause as compulsion, provocation, reaction, environment, upbringing, parents, circumstances …)
But, when you do something GOOD OR BAD, I tend to praise OR respectively blame you as though you acted freely, in either case.
People can be simultaneously responsible for their actions, and yet not exercising free will. Or vice versa.
As far as descriptive ethics goes, I think it is pretty accurate, and I'd say that the switch between holding a person responsible and viewing them as devoid of free will is governed by Strawson's Reactive Attitudes.