Pinker and modular theory.

The alternative to Pinker, Chomsky and other 'modular' theorists is not the "blank slate" straw man, but a more nuanced, interactionist, systems-theory account of biology and society. Human beings have evolved beyond simple evolved mechanisms such as instinct to develop a more adaptable social capacity. Cumulative cultural evolution can adapt much more quickly to changing conditions than can biological evolution, which is why humans are able to accommodate to practically any physical or logistical challenge in a very short period of time.

The problem with modular theory is essentially that they are unable to provide an account of what a module 'is', where it functions in the brain, and why a domain-specific module would exist at all (as opposed to more domain-general, flexible structures). Modular theory also has an inordinate focus on the brain as an isolated apparatus, whereas the evidence points to a brain that is sensitive to environmental factors; the expression of genes or evolved mechanisms is dependent on environmental feedback, particularly in complex, social species. Human minds are assuredly not a blank slate, but neither are they carved in stone.

Adoption is not an exception, but a counterexample. It's not a freak occurrence, but a phenomenon that is easily replicable given relatively common conditions. The fact that humans end up raising their own children is more a function of logistics and probability as it is of genetics (which is exactly why genetics doesn't need to play a role. The fact that pretty much anyone has the capacity to raise a non-related child, given the right circumstances, gives the lie to the idea that our ability to bond with children is a genetic 'program' dependent on relatedness.

Your problem is that you have just enough knowledge to think you know everything, but not nearly enough to have a comprehensive account of the issues involved. Pinker is not exactly cutting-edge.