Okay, so imagine you have a grandma, and she had a mommy, and her mommy had a mommy, and so on. And all these mommies were girls and they all lived a very very very long time ago, like when there were no TVs, cars or even dinosaurs. We call these mommies "ancestors."
Scientists have found out that all people have ancestors, and they can tell where these ancestors come from by looking at something called DNA. DNA is like a map that tells the body how to grow and work. It's kind of like a recipe book that tells you how to make cookies!
So, scientists looked at the DNA of a bunch of people and they found that ALL of these people have ancestors from all over the world, but they can all trace their ancestors back to just seven moms. These moms lived a really really really long time ago, and they are called the "Seven Daughters of Eve."
Scientists think that these Seven Daughters of Eve lived in different parts of the world, like Africa, Asia and Europe. They each had their own DNA, which they passed on to their kids, who passed it on to their kids, and so on, until it got to you and me!
So that's why some people look different from other people, like their eyes or skin are a different color. It's because they come from different moms, who lived in different parts of the world a long time ago, but they all had something in common: they are all ancestors of the Seven Daughters of Eve!