How did our son end up with *hazel* eyes?

[astro]

Hazel Eye Variations w/ pics

A hazel eye.Hazel is usually used to describe eyes that contain elements of both green eyes and brown eyes, in rare cases, also containing gray or blue, sometimes transitioning from green at the edges to brown around the pupil, and light brown. Hazel eyes often change color depending on what the person is wearing (i.e. if the person is wearing green or purple, the eyes appear mostly green). They are commonly found in middle European countries such as the middle of Russia, Belarus, Ukraine, south and middle of Poland, south and middle of Germany, north of France, Switzerland, north of Italy, Turkey, Slovenia and others.

Amber eyes
Amber eyes are often mistakenly referred to as “hazel.” They have, however, a much stronger yellowish/golden and russet/coppery tint than hazel eyes and are not as common in humans. The golden tint appears at its brightest in direct lighting or sunlight, but turns into a golden green-brown in the shade or a coppery brown in candlelight. Amber eyes are also nicknamed "cat eyes

So how might something like hazel eyes work? No one knows for sure but I’ll discuss some possibilities. But before that, it is important to go into a little detail about eye color.

Brown, green and blue eye color comes from a pigment called melanin. Brown eyes have a lot of melanin in the iris, green eyes have less, and blue eyes have little or no pigment.

Two genes, bey2 and gey, work together to make brown, green, or blue eyes. Each gene comes in two versions or alleles.

One form of bey2 makes lots of melanin (and is usually referred to as B) while the other form makes only a little (b). One form of gey makes some melanin (G) while the other makes only a little (b).
One of his eyes has B in some
cells and only b in others
So how do you get eye color from all of this? If you have B you get brown eyes, G but no B, green eyes and if you only have b, then you get blue eyes.

Most likely, hazel eyes simply have more melanin than green eyes but less than brown eyes. There are lots of ways to get this level of melanin genetically.

It may be that hazel eyes are the result of genes different from gey and bey2. Something like hey for hazel. And maybe hey is a bit like bey2 and gey in that it comes in two forms—one that makes enough melanin for hazel eyes (H) and one that makes little or no melanin (b).

If this were true, the scheme for eye color would have to be changed. In the new scheme, you would have brown eyes if you had B, hazel eyes if you had H but not B, green eyes if you had G but not H or B and blue eyes if you only had b.

My gut tells me this probably isn’t the answer. Even though this sounds pretty complex, it seems like it wouldn’t be that much harder to tease out than green and brown eyes. So it is probably something else.

Another possibility is a variation on this theme. Maybe hazel eyes come from different versions of bey2 or gey. I said at the outset that there were two versions of each gene. But what if there were more? What if there were many versions that result in the various shades of color we see?

This is certainly plausible and some recent research suggests that this might be part of the story. But again, I’m just not sure. I would think the genetics again would be easy enough that it would have been figured out by now.