One example being: the offspring of one parent with blond hair and blue eyes and another parent with black hair and brown eyes, is more likely to have black instead of blond hair, and brown instead of blue eyes.
Why are the black and brown genes stronger if both sets of genes make up 50% of the offspring?
Comments
It varies, depending on the gene, but one way it can work is if Variant A does something and Variant B does nothing. So, if you have 2 copies of A, you have two copies of of the gene that do something. If you have 2 copies of B, you have zero copies that do anything. But if you have 1 A and 1 B, you still have 1 copy that does something, so it does that something. This, I believe is the case for things like eye color. Having blue eyes is actually the result of just not producing pigment in your eyes, whereas having brown eyes is because you have at least one copy that says “make brown pigment in the eyes”. There isn’t a blue pigment in people’s eyes that are blue. That’s just what the Iris looks like without brown pigment.