If a person with blue eyes and one with brown eyes have a baby will the baby always have brown eyes?

So me and my friends were talking a couple of days ago. My friend told me her sisters baby came out with blue eyes, but this is were I got confused, because my friend had dark brown eyes, and her husband had blue, so I thought brown eyes over rule blue eyes, so either way if the woman has blue eyes or the man, your child is still going to have dark brown eyes? Or does it have to deal with the grandparents? because the husbands parents both have blue eyes, but the wife's mother has hazel and the husband has brown. so now I am very confused?


Most Helpful Guy

  • The brown gene (B) is dominant over the blue gene (b), so to have blue eyes, your genotype (both genes together) would have to be (bb). People with brown eyes can have either (BB) or (Bb) as a genotype. So the father had (Bb) and the mother had (bb). the dad carried the blue gene, but it disnt show because brown is dominant over blue. So his (b) gene crosses with one of mom's (b) genes to make (bb). Blue

    • In other words if the father or mother of the mum had blue eyes then it's possible that the kid has blue eyes. The mother would have the genotype of Bb.

    • Yeah yeah. Sorry I got the mom and dad confused.

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    haha it`s really kind of fun to caltulate this ^^

  • Well I don't know much about genetics and eye and hair coloring is always very complicated and I didn't really get past high school bio but basically brown eyes are dominant color and if one parent has brown and one has blue the baby is more likely to have brown because the brown gene is stronger but if it comes out with light eyes that means that the parent with brown eyes was a hybrid and he/she has a gene for light eyes which means that he/she either has a light eyed parent or a parent who was a carrier of the light eye color gene and he/she inherited it and now passed it onto this baby.

    So yes it is definitely possible, one brown eyed parent does not always mean brown eyed kids though the odds for brown eyed kids are higher than light eyes because of the dominance of the brown eyecolor gene. For example one of my parents has blue eyes and one has brown and I have greenish blue.