Having one blue and one green eye is called heterochromia, which is usually caused by genetic factors. It is usually manifested as the iris color of one eye (the iris is the colored part of the eyeball) being different from the iris color of the other eye.
Heterochromia (different colored eyes) is caused by genetics. Iris color is primarily influenced by two types of genes: the gene for melanin production and other genes that determine iris color. In some cases, an individual may inherit different iris color-related genes from their parents, resulting in different eye colors.
