Cultures don't just "happen". Culture is a deliberate act of founder instilling company values in early employees, so the culture then scales from there. Best cultures always feel natural, because founders and early employees spend a boat load of time working on it and enforcing it.
15 years and 9 startups, I walk into the company and immediately can tell if I want to be there. Companies without culture are usually those in a Fortune500 list - numb, bland, like Hondas and Toyotas.