Eye Colors 2001227
I am understanding more about eye color and what we know so far. As an
example My wife has brown eyes, and I have green eyes. Our baby has blue
eyes. From what I have gleaned from other research is that is typically a
25% chance of occurrence based on what we know today. I have a sister
who has blue eyes, and my wife has two brothers who have blue
eyes. Neither of our parents have blue eyes. Her side Brown and hazel,
and my side both green. With Brown as a dominant (if that is true) how
does all this work?
I have also heard (not read) that for two Non-blue eyed parents to have a
blue child BOTH would have to have recessive blue.
Is that true?
By recessive I mean blue has been found in the previous generation of
siblings or parents. So do I understand recessive correctly?
Are we certain about what produces what at this time?
Some information can not explain why two blue eyed parents can produce
brown eyed children.
We also cannot explain all colors like gray, hazel, multi shades etc
We know that the inheritance of eye color is much more complicated than once
believed. It is not under the influence of just one gene, or else people
would be either brown eyed or blue eyed. This also does not account for the
difference in shades of eye colors. Now it is believed that eye color is a
polygenic (many genes) trait and it depends on how many active (additive)
alleles(versions) you inherit. By the way, blue eyes is really an absence
color, similar to the way water appears blue by reflection but is really
So people with blue eyes have not inherited any or very few
alleles. The more active alleles that are inherited the darker the color of
the eyes. Let us say that mom has medium brown eyes and dad also has medium
brown eyes, but each of them have 3 active alleles and 3 non active alleles.
Let's say then that their first child inherits all 6 of their active alleles
and has dark brown eyes. Let us say that child number 2 inherits all 6
non-active alleles. That child will have very light blue eyes. Green,
hazel, gray, light brown, etc. are all as a result of how many alleles are
adding to the eye color.
This is also why brown is always dominant over
and green is dominant over blue because they both have more active alleles
than blue and add to the eye color.
Click here to return to the Molecular Biology Archives
Update: June 2012