Marx introduced an important corrective into German philosophy, and re-oriented the task of emancipation to the socio-political milieu. The philosophical analysis of freedom had been up in the clouds for a generation, since Kant's essay "What is Enlightenment?". Marx talked about freedom as fundamentally grounded in actual history, instead of being interwoven with complex metaphysical and epistemological speculations. I think this was an important contribution, but I see no reason to accept a totalizing position on either end of the spectrum.

I think clearly both factors affect each other. There's a clear reciprocal relationship between our neurological development and our experience, for example. Take a simple case - we know on the basis of empirical research that during development, the growth of dendrites in the brain is stimulated by touch provided by caregivers. We also know that neural development is quite plastic, and the development of our brains depends very much on our situation and context. Those are clear examples in which our "social being", as it were, determines our mental being.

I hope that the degree to which our social being delimits or constrains our consciousness is obvious to any educated member of our culture, at this point. I think Marx has clearly won that battle.