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what should my babys eye color turn out to be if me and my girlfriend both have light brown eyes?

(2 posts)

  1. Dresden Rose
    Member

    It is genetically impossible for two brown-eyed people to have a blue-eyed baby.

    Your baby's eyes will be brown.

    Posted 1 year ago #

  2. Dan B
    Member

    Hi there,

    Dresden Rose is incorrect. At the moment 3 human eye color genes are currently known and named:

    -EYCL1 (gey, NO NOT GAY NOR GREY)
    Gene responsible for Green/blue eye colour, located on chromosome 19.

    -EYCL2 (bey1)
    Gene responsible for what is called central brown eye colour, located on chromosome 15.

    -EYCL3 (bey2)
    Gene responsible for Brown/blue eye colour located on chromosome 15.

    The standard way of working out what the possible offspring of two parents is the Punnett Square. Since each individual has one pair of each chromosome, they have two copies of each gene (1 on each chromosome). Since eggs and sperm each carry only one of each chromosome, they carry only one copy of each gene instead of two. Thus a female who carries two different flavours (we call these flavours alleles) for a particular gene, produces some eggs that carry 1 flavour, and some eggs that carry the other. The same is true for male sperm.

    Ok so to make this simpler (I hope) we will think of it this way. When determining eye colour we use the 2 gene model meaning there are 2 genes involved in eye colour. Because chromosomes come in duplicate pairs, each parent has two copies of each gene. So when the egg is fertilized that egg will have 1 of the 2 genes. The same is true for the sperm.
    Also remember that some genes are DOMINANT (will take over and dominate) while others are RECESSIVE (submissive). Thus if you have Brown/blue as your genotype, since brown is dominant over all others (followed by green), then Brown will also be what you see although genetically you have 1 gene for blue colour.

    In terms of Dominance: Brown Dominant over Green which is Dominant over blue.

    Keep in mind that GENOTYPE means what genes are present. PHENOTYPE described the physical characteristics.

    So for Brown Eyed People

    bey2 Gey
    Chromosome 15 Copy 1: Brown Chromosome 19 Copy 1: Green
    Chromosome 15 Copy 2: Brown Chromosome 19 Copy 2: Green

    Chromosome 15 Copy 1: Brown Chromosome 19 Copy 1: Green
    Chromosome 15 Copy 2: Brown Chromosome 19 Copy 2: blue

    Chromosome 15 Copy 1: Brown Chromosome 19 Copy 1: blue
    Chromosome 15 Copy 2: Brown Chromosome 19 Copy 2: blue

    Chromosome 15 Copy 1: Brown Chromosome 19 Copy 1: Green
    Chromosome 15 Copy 2: blue Chromosome 19 Copy 2: Green

    Chromosome 15 Copy 1: Brown Chromosome 19 Copy 1: Green
    Chromosome 15 Copy 2: blue Chromosome 19 Copy 2: blue

    Chromosome 15 Copy 1: Brown Chromosome 19 Copy 1: blue
    Chromosome 15 Copy 2: blue Chromosome 19 Copy 2: blue

    Example of how a child from TWO BROWN EYED PARENTS could have a BLUE EYED child. What I must do is separate all the possibilities and then cross them. So as previously stated egg has 1 of 2 possible genes from mom, sperm has 1 of 2 possible genes from dad.

    Parent 1: Physically has Brown Eyes, Genetically Has: Bey2 (Brown-blue), Gey (Green-blue)
    Parent 2: Physically has Brown Eyes, Genetically Has: Bey2 (Brown-blue), Gey (Green-blue)

    Both parents are physically and genetically the same. Remember eye colour is determined by 2 genes this is why genetically they have Bey2 and Gey.

    bey2: Brown Brown blue blue
    gey: blue Green Green blue

    Brown Brown-Brown Brown-Brown blue-Brown blue-Brown
    blue blue-blue Green-blue Green-blue blue-blue
    (Brown Eyes) (Brown Eyes) (Brown Eyes) (Brown Eyes)
    Brown Brown-Brown Brown-Brown blue-Brown blue-Brown
    Green Brown-Green Green-Green Green-Green Blue-Green
    (Brown Eyes) (Brown Eyes) (Brown Eyes) (Brown Eyes)
    blue Brown-blue Brown-blue blue-blue blue-blue
    Green Brown-Green Green-Green Green-Green blue-Green
    (Brown Eyes) (Brown Eyes) (GREEN EYES) (GREEN Eyes)
    blue Brown-blue Brown-blue blue-blue blue-blue
    blue Brown-blue Brown-blue Green-blue blue-blue
    (Brown Eyes) (Brown Eyes) (GREEN EYES) (BLUE EYES)

    Remember GREEN IS DOMINANT OVER BLUE.

    75% chance of brown eyes and a 18.75% chance green eyes and a 6.25% chance of blue eyes. About three quarters of the children of this cross will have brown eyes, three sixteenths green eyes and one sixteenth blue eyes.

    I hope this helped a little, the truth is if you do not know anything about genetics it is confusing. Also they do not change as they get older. Maybe different shade but that is it.

    Posted 1 year ago #

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