I know that Mendelian genetics are quite a bit more complicated than the simple patterns I learned in biology 101, but this has thrown me for a loop. I have dark brown eyes, as do all members of my immediate family (my mother, father, and two sisters); DeathLlama has bright blue-grey eyes, like his mother (his father has brown eyes, and DL has no siblings).
We figured our little RuffLlama would likely have brown eyes, though there was a possibility of blue (my aunt, cousin, and grandmother have blue eyes). But I’m thrown off that our 4 1/2-month old son appears to have hazel eyes–that is, blue-grey with brown flecks, giving a forest green appearance from a distance. I didn’t think hazel was a possible outcome. He actually looks like someone took my husband’s eye color as a background, and sprinkled my eye color over top. I didn’t think a “mix” was possible genetically.
This website predicted that there was a 72.7% chance our son’s eyes would be brown, and 13.6% chance each that they could be green or blue. It’s a pretty simple calculator–it doesn’t take extended family into consideration–and it doesn’t really help explain where RuffLlama’s eye color came from.
FTR, I know eye color can change a lot the first year. I don’t think his eyes will be brown, however; every child in my family born had obviously dark brown eyes by two months.
The Medelian genetics for general eye-color are not “Brown” or “Blue”, but “Brown” or “Not-Brown”. Blue, hazel, green, yellow and purple are the possible “not brown” eye colors. The details of which of those colors your child’s eyes will be is left up to other genetic and physiologic factors - the amount of lipids in the iris, among other things. So the chances of any of those other colors are included in the 13.6% - blue and hazel being by far the most common. (I’ve only known one true yellow and one true purple eyecolor personally.)
So it’s perfectly possible his eye coulds stay hazel. Then again, they could still change. Only time will tell.
Well, the leftover 27.2% (it was 13.6% each for blue or green).
According to the site I linked, green is dominant and only blue is recessive, at least, that’s what I’m assuming in the bbbb bbGb bbGG BbGb BBGb patterns. Brown just appears to be, erm, more dominant. Is that an accurate-ish assessment?
I’m also curious what other genetic factors affect eye color (lipids in the iris, perhaps?).
BTW, I remember reading ages ago thatPeter Cetera (lead singer ofChicago) has yellow eyes. Trippy. Wonder how the heck that comes along, genetically, and if the parents weren’t freaking out about it just a little.
You have brown eyes, but that doesn’t tell you anything about your full genotype. You may very well have one of the many “not brown” alleles that is hidden phenotypically by one “brown” allele. The wikipedia article on eye color is pretty good, btw.
From Mendel’s early work with peas, we drew a lot of general conclusions about dominant and recessive genes. Working with those generalities, many parents got into false accusations about a charming baby’s father’s identity.
Knowledge about genetics has gone through massive growth in the last few decades, and now we know that Mendel’s rules only go so far. Determining human eye color, for example, is a lot more complicated than a Mendelian chart. There is no point in trying to find out GreatGramaLlama’s eye color, or the mailman’s. Just accept what you got, and don’t try to explain it.
As was said, eye color is much more complicated than simple Mendelian genetics. I will give my family as an example. My eyes give the impression of being blue, but they have brown flecks, small and not many. My wife’s are similar, but just enough more brown flecks to leave an overall impression of green. My father’s were similar to mine, but my mother’s were brown, although her father was a blue-eyed blond (and pure–so far as is known–Ashkenazai Jewish as were all of us). Of my three kids, one appears to have brown eyes (but the brown is anything but uniform and a close look shows that they are just brown enough to give that overall impression). My two boys both have nearly pure blue eyes.
hair color is just as bad and one of the boys is pale blond, while the other two are dark brown. I am dark brown and my wife is dirty blond.
For something more bizarre, it is perfectly possible, although rare, for two blood type O parents to have a type A or B (or much rarer, even AB) blood. However, everyone in my family whose blood type I know has type A.
from my own family i can say, yep, brown and blue creates hazel. now, when those hazels all married blues (strange that), we ended up with a range of grays and blues. some of them are changeable, going gray-er or blue-er with emotion, light, or apparel.
That would be quite a feat since Ruffian and Shirley Booth are both genetically XX. Well, not the quickie part, but the having-a-baby-as-a-result part.
(I assumed you wanted to say "two blood type O parents to have a child with type A or B (or much rarer, even AB) blood. )
(bolding mine)
Is this possible? Correct me if I’m wrong but isn’t type O blood a recessive trait? So if both parents have a genotype (aa), how does one pass along a dominant alelle to make type A, B, or AB possible?
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.
I’m going to go read the wikipedia article, but this ‘Brown’ and "Not-Brown’ thing is interesting. My husband and I both have brown eyes, and our son has blue eyes. Both of our mothers have blues eyes, so I always figured we both carried some ressesive blue-eyed gene that popped out for him. Is that what happened?
That’s exactly what happened (as I remember it). If he marries a blue-eyed girl, they will have only blue-eyed children, because it takes blue/blue to get blue eyes. I hope I got that right.
I have a brown-eyed dad and a gray/hazel-eyed mom. I got green eyes out of the deal. Go figure.
My whole family that we can all recall have brown eyes (my mom, dad, grandparents on both side, etc, sister, brother) but I have hazel. I personally think my Mom was sleeping around.
This can still be explained. I used the eye color calculator linked in the OP and it spit out that 5.5% of your parents’ offspring could have green eyes. In astro’s link about how hazel eyes might work, the author supposes that there’s a moderator gene M that works on the green gene G to turn it into hazel. Since M has no effect on B (brown) or b (blue), it could hide in your ancestors’ genomes for quite a while before showing up with you.
Of course, it could be that your mom was sleeping around, but your having hazel eyes doesn’t definitively prove that.
Maybe I’m just defensive, as when I was in 5th grade another kid told me I had to be adopted because my parents had brown hair and brown eyes and I had blonde hair (which has darkened quite a bit since) and blue eyes.
