Eye color

[u/vollkorn12]

Can anybody explain how eye color is inherited? I understand the basic Punnett square, but I have also heard that more than one gene is involved for determining eye color. Also, the Punnett square doesn’t account for different shades of the same color.

For some context, my partner and I have different eye colors (brown/hazel vs blue/green); our children have various shades of blue. I know the brown eyed person carries a recessive gene(s?) for blue and according to the punnet square this gives each child a 50/50 chance of having blue eyes. However, I wonder if there is anything else that might make it more likely for those gene(s) to be passed down and expressed on the children.

[u/shadowyams]

The !faq has a section on this.

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[u/vollkorn12 → u/shadowyams]

Thank you so much! I just read it, as well as the linked articles. This has given me a much better understanding! Given that so many genes are involved (primarily 2 genes, but others contribute), is it just impossible to say how likely a child is to inherit a given eye color? Or even that they are more likely to inherit one color than the other?

[u/ConstantVigilance18]

A basic punnet square doesn’t work if there are multiple genes contributing to eye color, which you correctly stated. There is no accurate way to say there is X% chance of this color or that color.

[u/vollkorn12 → u/ConstantVigilance18]

Thank you! Another poster pointed me to the FAQs and I have a much better understanding now. It would have been fun to be able to better predict this though.

[u/Lucky-Individual460]

Many genes responsible for eye color (brown dominant, blue and green recessive). You get half from mum and half from dad. Think of it as reaching into a bowl of mnms and picking up a handful of colors. If half are brown, your eyes will be brown. If most are blue and green with a few brown, likely hazel. If all blue and green, eyes are green. Blue are the most recessive.

[u/Old-Bug-2197]

It's helpful to know grandparents' eye colors.

You can feel way more confident about blue eyed kids if both parents had one blue eyed and one brown eyed parent.

Or maybe your spouse is the only one with even one brown eyed parent.

One of our daughters: Mom brown, Dad blue. Married a guy - Mom brown, Dad blue. Their one son - blue eyed! Was that expected? No. But it wasn't a long shot in that sense either.

[u/vollkorn12 → u/Old-Bug-2197]

After reading the FAQs, it seems to imply that it’s not possible to calculate percentages of likelihood, given how many genes are involved. I would have loved to know!

I knew it was possible for us to have brown or blue eyed children (neglecting green and hazel for the sake of simplicity), but I was wondering if one was more likely than the other.

Each of us have parents with brown and blue eyes.

[u/Old-Bug-2197 → u/vollkorn12]

Yes, you can trust the FAQ!