Brown-eyed parents can have a blue-eyed child... two reasons!
Absolutely two brown eyed parents can have a blue eyed child. It happens all the time! The reasons can go a couple ways...
If we're talking about a baby, of course, many babies are born with blue eyes even if it isn't their 'actual' eye color. The same stuff that makes you look tan (or freckled as is my case), melanin, also accounts for some eye coloring. Not only is all the melanin that will be present in the iris not always fully there yet at birth, a baby who has been in the womb for nine months also hasn't been exposed to much sunlight.
Just like melanin turns your skin in sunlight, it will also darken your baby's eyes if they have the genes for it! Now, as for why our eyes don't get pale like our skin when not exposed to sun for a while, I don't know. If anyone does, please tell me! My proposed theories- maybe they do get paler and I've never noticed, nothing to slough off the color in our irises the way we do dead skin... that's all I have, but no idea for sure on that part!
Anyway, as far as genetics go... Two brown eyed parents can definitely have a blue eyed child. Brown eyes is a dominant gene, while blue eyes is a recessive one, meaning that brown eyes will 'overtake' blue eyes in how that gene is expressed. From here on out B will be the dominant Brown and b will be the recessive blue type, or allele, of the gene.
So, each parent has two forms of the gene (they may both be the same, but I'll get to that in a minute) and 'donates' one to the child, so the child will also have two.
Now each or one parent may have two Browns (BB) which will most likely result in a brown eyed child. (Green is a weird one to figure out) BUT. Since blue (b) is recessive each parent may carry the blue allele but still have Brown eyes since it is the dominant gene. Therefore their genotype will look like Bb for our purposes, one Brown and one blue.
So, if each parent passes on one of these to the child... here are the possible combinations the child may get.
BB= Brown eyes for baby, Brown from mom & dad,
Bb= Brown eyes for baby, Brown from dad, blue from mom.
Bb= Brown eyes for baby, Brown from mom, blue from dad
bb= Blue eyes for baby, blue from mom & dad
So, there's a 75% chance that the parents will have a brown eyed child, but a 25% chance baby will always have blue eyes even past the point melanin would set in and take on color.
Perfectly natural, so no worries!
Any mamas out there with brown eyes who have a blue eyed babe? What color eyes do his or her dad have?