Does anyone know about genetics in eye colour?

Question

I want to know what chance I have of having a blue eyed child. Both my parents have brown eyes but I have blue. If the father of the child has brown eyes, what are the chances of the child having blue eyes? If he has blue eyes, is it definite that the baby will have blue eyes or could it still have brown eyes?

Answer 1

There are two primary genes involved in eye color:  B and G

Each person has two alleles for each gene.  So, you can be BBGG or BbGG or bbGg or Bbgg, etc.

If you are dominant at the B gene (so BB or Bb) then you have brown eyes and it doesn't matter what you are at the G gene.

But, if you are homozygous recessive at the B gene (bb) and dominant at the G gene (Gg or GG), then you have green eyes.

To have blue eyes you are homozygous recessive at both genes:  bbgg.

So, if you have blue eyes, then you give your baby a b and a g allele.  If the father has brown eyes, all you really know about his genotype is that he has at least one B allele, but he could be:

BBGG - all your children would have brown eyes

BBGg - all your children would have brown eyes

BBgg - all your children would have brown eyes

BbGG - 50% chance of brown eyes, 50% chance of green in children

BbGg - 50% chance of brown, 25% chance of green, 25% chance of blue

Bbgg - 50% chance of brown, 50% chance of blue

If the father has blue eyes, then he would have your same genotype: bbgg.  This means that your children could only get b and g alleles and would therefore have blue.

There are some other minor genes involved and environmental interactions that affect shades, but the primary color is determined by these two genes.

Answer 2

Eye color is not caused by a single gene.  If it were,  then there would only be two varieties of eye color....  for exmple:  "Gene A's" dominant color (dominant allele)  and a "Gene A's recessive color (recessive allele).

Because of this,  you cannot predict or plan your child's eye color that simply.

A punnet square isn't going to do it.

You can look at probabilities.

Your parents were both carrying the recessive blue gene.... you just happened to get a combination of these from BOTH parents.  Another child from them may not get this combination again.

Answer 3

If the father had blue eyes then the baby will 100% have blue eyes. If the father has brown eyes the chance of can vary depending on whether or not his parents had blue eyes. If one did then its a 50-50 chance for blue and brown but if both parents had brown eyes then its 100% that the baby will have brown eyes. If his parents had any color of eyes other than blue or brown it would be extremely hard to tell without knowing what many of his ancestors eye colors were.

Hope this is clear enough for you to understand.

Answer 4

i think the chances are that she/he will have brown eyes. heres how:

every one has two types of genes for something. like for eye color, your parents have blue and brown, and you happened to recieve the two blues. brown is usually dominant, but i dont know how you got blue. or you may be adopted (jk, but i know a person like that. she found out she was adopted in college when the teacher was talking about genetics). if your husband has brown, then it might be brown. unless he has 1 brown and 1 blue. you get get 2 genes from your parents, and thoses 2 genes you get determines.

if your husband has 1 brown and 1 blue, then the ration MAY be 3 blues to 1 brown. so blue may win at that.

i think it depends on the ratio and dominance.

so i think it may be 50/50, but i also think brown may win.

but i think that the eye color your baby gets will be the best for her.

good luk

Answer 5

The problem is that brown and blue eyes are not a simple one gene dominant/recessive trait, but a complex interaction between probably as many five pairs of genes for intensity and as many for pigment distribution which alters the apparent color.

The idea that is still taught in many schools of a simple brown or blue is what leads to the kind of confusion shown in this question