system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Eye Color Genetics

ELI5: My mom has green eyes, my dad (RIP) had blue eyes. I also have blue eyes, but my sister has brown eyes. I understand basic eye color genetics (blue and green eyes are recessive, brown are dominant) but how can two parents with recessive eye color traits have a kid (my sister) with a dominant eye color trait? No, she is not adopted, theres no scandal here. No milkmans baby or anything like that as far as I know. Is this possible? Please ELI5, thanks.
gpt
Eye colors are a bit more complicated. There's a separate set of genes that controls how melanin (the protein making your eyes brown) is packaged. If this gene is mutated (double recessive), you will have light colored eyes even if you have the dominant brown eyes gene.

For example, let's say P is dominant good packaging and p is mutated bad packaging. B is dominant brown eye and b is blue eyes. You need at least one capital P and capital B to have brown eyes.

If your mom was Ppbb (blue eye due to two recessive color) and your dad is ppBb (blue eye due to mutated packaging), your sister with PbBb would have brown eyes with a 25% chance! The other 75% chance would have blue eyes.