The Genes That Bind

Genetics is fascinating. I remember back in the good old days, in biology class in high school, learning about dominant and recessive genes and how we pass on characteristics to our kids. Most of our instruction revolved around the green bean study done by whoever it was that studied green bean genes way-back-when, although we did talk about eye color and the fact that being able to curl your tongue is genetic. Good thing, too, since I thought I didn't have that talent and it turns out I just don't have that gene!

It all seemed so black and white then. Of course, when you get out into the real world, you learn that there are infinite shades of gray no matter what the subject.

I have dark brown eyes, which I had been taught was dominant over each of my baby daddies' blue eyes. Yet only two of my five kids have brown eyes. How did that happen? In #4 (and now #5), that brown eye gene was "overpowered" by the also dominant Waardenburg contributed by DH, which typically brings sapphire blue eyes. However, that doesn't explain why #1 (whose father has no such syndrome that we know of) has eyes that changed over the years from blue to gray to hazel even after most people's eye color is set. Chameleon eyes? How can they keep changing colors? (Clue: Recombination explains the brown/blue versus hazel, one of those mysteries high school biology class did not cover in the green bean discussion.) And what about #3, a full sibling to #4 and #5, who had sensorineural hearing loss at birth but has brown eyes, no white forelock, and years later went on to have normal hearing? Does she have a "broken" Waardenburg gene, or does recombination factor in there, too? Only #2 has "fit the mold" with dark brown eyes.

Anyhow, that dominant Waardenburg gene seems to have found its way into #5. I knew it when I saw her white forelock and eyebrows. Her newborn hearing screening was a "refer," so yesterday the audiologist did some more testing. She definitely has hearing loss, but we need to set up a tone-burst ABR to determine how much and whether she has enough residual hearing to benefit from hearing aids. Not looking real optimistic there, since she failed on all the sounds....

In any case, it's all still fascinating. I need to go read some more now, to satisfy my rabid sense of curiosity on brown versus blue and WHY.