It's true. But in a sense, everything is an act: the behaviors that might sometimes feel a little phony in adulthood, but are still easily maintained with only the barest hint of conscious thought, were completely unknown in infancy, but, as we witnessed them thousands to literal millions of times, were eventually engraved so thoroughly into our pattern recognition systems that we can no longer make any true conception of being without them. Indeed, phoniness marks the tip of the iceberg: nurture affects to some extent all morality, emotion, and logic, even those aspects that seem the most pure and natural; true, we can deduce from evidence like universality among cultures, the behavior of animals, evolutionary principles, etc. that some of it is truly hardcoded into our genes, but there are no sharp boundaries...
Not that any of that is a bad thing. But in a sense, 4chan is a simulation of what we could all really, honestly be like in a different environment - to the extent it's fueled by acting, it's just compensating for the fact that nobody is raised there from birth.