The honest answer is: both. The people around you and the culture you grow up in give you language, categories, values, stories, and habits of thought long before you ever stop to examine them. In that sense, your culture helps you think by giving you a place to start. The common saying that we stand on the shoulders of giants points to the same truth: as society grows more advanced, each newborn inherits more and more. We are all handed a ready-made world of meaning. That is a gift, but it is also a danger.
Back in 1966, Peter Berger and Thomas Luckmann helped put this problem into focus in The Social Construction of Reality. We are not born into a blank world. We are born into a social world already stocked with “what everybody knows.” Some of that common sense is wise and hard-earned. Some of it is mistaken, tribal, fashionable, or flat-out false. That means critical thinking is not just about learning facts. It is also about learning to notice which parts of your social inheritance deserve trust, and which parts need to be challenged.
So yes, your people and culture can sharpen your mind, but they can also quietly train it to stay inside approved boundaries. They can hand you truth, but they can also hand you slogans, blind spots, and emotional loyalties dressed up as reality. Critical thinking begins when you realize that what feels normal is not automatically what is true. From there, the job is not to reject your inheritance, but to examine it carefully and sort it with honesty.