Why are most (all?) babies born with blue eyes? How long will they stay blue until the eye color is considered permenant (up to a year according to a book I read on Nazi experinments, but that was hardly a scientific text). Finally–I’m hoping this answer doesn’t get too technical–how would one determine the probability of one’s baby’s eye color. For example, I’m blue-eyed and don’t know my parents’ eye color, my wife has brown eyes, as does most of her family, so . . . ?
I guess I want to know if my baby’s eyes will stay blue or not, for how long, and why or why not. We covered this years ago in science class but I wasn’t the best student, what with girls and alcohol and everything . . .
Could somebody please help me fight my ignorance on this subject? Thanks in advance.
Lets see. Your wife has brown eyes and most of her family has brown eyes and you have blue eyes I assume although I don’t recall you saying so. So your wife may/most likely has 1 dominant brown and one recessive brown gene. You have one blue dominant gene and one ? gene. So if they pair up (wife on left/you on right:
Dominant brown/dominant blue = Brown
Dominant brown/? = Brown
Recessive brown/dominant blue = Brown
Recessive brown/? = Brown
Let’s hope just to give you a better chance that your wife’s recessive isn’t brown.
Caucasian babies are pretty much all born with blue eyes (as are kittens and perhaps other mammals) simply because the enzymes responsible for causing other eye colorations haven’t finished developing yet. In other words, they all have blue as a base color and the later color simply blends/covers the blue. Asian and black babies are born with darker eyes that don’t change much as the child matures.
Going on memory (and very simplified- eye color involves more than just blue and brown)
Your eyes are blue- two recessive genes for blue
Your wife’s are brown- maybe two brown genes, or one brown and one blue.
If your wife has two brown genes, all the children will be brown/blue and have brown eyes. If she’s brown/blue, there’s a fifty percent chance a child will also be brown/ blue and have brown eyes, and fifty percent that the child will be blue/blue and have blue eyes.
Doreen
In most cases, eye color is established by 6-9 months (earlier for dark colors, later for light colors - don’t know why that is), but may well continue to shift within the color range well into adulthood, and in some cases shifts later than 9 months (rarely shifts significantly after 3 years, though, IIRC).
Gender is the only thing determined soley by the male’s genes. Males have an X chromosone and a Y, while females have two Xs. A baby, then, is bound to get an X from the mother, and either an X or a Y from the father, which will determine the baby’s gender. There are some traits, though (hemophilia and color blindness are examples) which predominantly strike males, and are inherited mostly from the mother. These are carried on the X chromosone: The X is pretty much a complete chomomosone, with genes for all sorts of traits, but the Y carries (almost) nothing beyond the traits for maleness. So far as I know, eye and hair color are on some other chromosone, so there’s nothing gender-specific about them.
If you have blue eyes, then we know your genotype, since blue is recessive: The only way to get blue eyes is to have two blue genes. Before you had your baby, your husband’s genotype wouldn’t have been known (although it might be determined from looking at his relatives), since there’s two ways to get brown eyes. You can have two brown genes, or a brown and a blue, since brown is dominant. If he were brown-brown, then your daughter would be guaranteed to be brown-blue, one from each of you, which would show up as brown eyes. If he is brown-blue, then your daughter will be either brown-blue (brown eyes) or blue-blue (blue eyes), with a 50% chance of either. So, if your daughter keeps her blue eyes, we can conclude that your husband has genotype brown-blue, and any future kids you have will have a 50-50 chance for either. If her eyes turn brown, then we don’t know what her father’s genotype is.
My father has brown eyes, as did everyone else in his family. My mother has blue eyes, as did both of her parents. When I was a baby until around the age of five or six, I had bright blue eyes. Now I have green. Not light-green-almost-blue, not brown-green-kinda-hazel, but dark green, like a pine tree. When I am tired, they turn blue.
