is it genetically possible for two blue eyed parents to have a brown eyed child?
- Anonymous1 decade agoFavorite Answer
Eye color is an inherited trait influenced by more than one gene.Certainly the model learned in school about brown-eye color being dominant over blue falls is an over-simplification. Indeed the one-gene theory is not valid; there is no single gene for eye color. There are two major genes and other minor ones that account for the tremendous variation of human eye color.In humans, three loci associated with eye color are currently known: EYCL1, EYCL2, and EYCL3.These genes account for three phenotypic eye colors (brown, green, and blue) in humans.Eye color is demanding, as all four genes must determine the same color for the eye color to be pure; otherwise a mixed color such as hazel will result.Eye color usually stabilizes when an infant is around 6 months old.
In 2006, the molecular basis of the EYCL3 locus was resolved.In a study of 3839 people, researchers reported that 74% of total variation in eye color was explained by a number of single nucleotide polymorphisms (SNPs) near the OCA2 gene (OMIM: 203200). OCA2 was previously known because, when mutated, the gene can result in a type of albinism. The recent study showed that different SNPs strongly associate with blue and green eyes as well as variations in freckling, mole counts, hair and skin tone. The authors speculate that the SNPs may be in an OCA2 regulatory sequence and thus influence the expression of the gene product, which in turn affects pigmentation.
So it is possible.Source(s): http://en.wikipedia.org/wiki/Eye_colour
- rainy-hLv 51 decade ago
Yes it is possible, though not common. The thing you were taught at school about dominant and recessive genes was a simplification of the real situation which works generally in most cases, however genetics is a bit more complicated than just adding up! So blue-eyed parents can have a brown-eyed child, ginger parents can have a brunette child, dark-skinned parents can have a light-skinned child, and my freaky cousin has an eye of each colour! Hxx
- Anonymous1 decade ago
Yes it is possible, but it relies on the chance (which is low) that the brown eye pigmentation allele (type of gene - every one has 2 alleles for each gene) is the recessive gene, which it isn't (normally but with random mutation it is possible).
Basically, the Parents would have the alleles for eye pigment of
Blue and Brown (mother) and Blue and Brown (father). If the Blue is the dominant allele then the blue would show regardless of the other allele. However, when the gamates (sex cells - sperm and ovum) are produced by miosis, there would only be 1 allele present, this would have to be the Brown allele in both the mother and father's gamates.
These gamates would have to fuse and produce the offsping which would have both the Brown alleles thus expressing this recessive trait.
This is unlikely because of the small chances of both brown gamates finding each other, but 100% possible.
- ZarathustraLv 51 decade ago
Putting aside the tiny possiblities of mutation. Simple mandalien genetics indicates it is impossble. All those who say the gene can come from others or the grandparnt ect, have no understanding of genetics.
In the real world ( again ignoring the 1.000,000 chance of mutation) if your eyes are blue and your childs are brown, don't try to convince a blue eyed man that he is the father.
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- sicoll007Lv 41 decade ago
One of the questions you need to ask is 'does any of the parents of the two blue-eyed people have brown eyes?'
If the brown gene is dominant, then their parents are likely to have brown eyes.
If the parents of the blue-eyed parents have also got blue eyes, then there is unlikely to be any brown genes.
If the parents (either one of them) of the parents have brown eyes, then there is a dominant brown gene which is very unlikely to express itself twice in following generations.
- ☞H.Potter☜Lv 61 decade ago
It really depends on what colour eyes your and your partners parents and grandparents had. Generally speaking it is almost impossible for blue eyed parents with a family history of that eye colour to have a brown eyed child. Remember that a baby's eye colour is not 'set' until they are approx' 3 months old.
- NénupharLv 41 decade ago
Blue eyes are caused by a a recessive gene that says to the developing cells "no pigment in the eyes".
Brown eyes have brown pigment, which is a dominant gene, especially in current American populations.
So if the brown dominant gene is strong enough, it can span several generations without showing in parents until the right combinations happen in one child.Source(s): It happened to me and I researched it. Dark brown eyes!
- Daniel RLv 61 decade ago
It is conceivable, but very unlikely.
In order for someone to have blue eyes, they must inherit the blue-eye gene from both parents. This means that they don't have a brown-eye gene at all. So if both parents are blue-eyed, neither will have a brown-eye gene to pass on to the child.
So the only way for this to happen is for a mutation to happen in the genes that make up the child. But having any specific mutation is extremely unlikely - the average person has about 150 mutations, but this is among thousands of genes most of which don't have any physical effect.
- Veronica AliciaLv 71 decade ago
My daughter has tawny eyes (yellow-brown, leonine), her husband has dark brown eyes.
Their first-born, a daughter, has dark brown eyes; their son has blue eyes.
I have green eyes, my husband has blue eyes.
My father had blue eyes.
I guess the recessive blue-eye gene had the last laugh!
Since the brown-eye gene is dominant, I think the parents could point a finger of blame at grandparents. Or Mendel!!
- Anonymous1 decade ago
yes because blue is recessive to brown and if a grandparent has one dominant brown they will get it. If 2 grandparents have a recessive brn it will skip a generation and show up in the grandchildren as a dominant gene.