Sisters, But Not Twins, In Iowa From their phenotype, it is obvious that these two girls share many of the same genes, as their blond hair and facial features are strikingly similar. And you can see that they are not twins; Lucy is 7 years old and Ellie is only 4. It may not be obvious that they have the same parents, but they do—and they are both very bright and happy because of it. This photo also shows that their genotypes differ in one crucial way: One of them has a dominant gene for a serious condition.