No, not everyone who has blue eyes is related. In fact, blue eyes are a result of a single genetic mutation that occurred around 6,000 to 10,000 years ago. Since then, this mutation has spread rapidly; today, up to 17% of the world’s population has blue eyes.
The mutation that causes blue eyes is thought to have originated somewhere around the Black Sea region and spread among people in the area. It is believed that the mutation was at first recessive, which means both parents had to have the gene for the trait to be expressed in their offspring.
Because blue eyes are so common, it is impossible to trace them back to a single source. However, since blue eyes are primarily found in Europe and parts of Asia, it is thought that people of European descent are more likely to have the gene.
Even within the same family, blue eyes may be expressed differently. For example, some people may have a deep blue color, while others may have a lighter shade. Additionally, the color can even change over time, becoming lighter or darker as time passes.
Although this mutation is found in many people worldwide, it is not true that everyone with blue eyes is related. Instead, the mutation is simply a result of a common gene found in many different people, regardless of their background or heritage.