Why do cats have so many different types of personalities?

Every cat is different, just like every human being is different. They have different genes, and grow at different environments. Though they are so different, they share commonalities. Most of them are natural hunters, very curious about their surroundings. They are often sweet and cuddly with human. Sometimes they don't listen well, because they are still not fully trained by human after thousands of years. Some cats love to play catch, while some others like to lazily laying under the sun.