Originally posted by serbsta
reply to post by Monts
Originally posted by Monts
The only way your guaranteed to have a child with blue eyes is if both your parents have blue eyes.
That can't be right. Neither of my parents, nor my grandparents have blue eyes, yet I do. I don't know who taught you that but it certainly doesn't
comply with my situation. 
The genetics of blue/brown eyes are thus (you only have to look in a high-school biology book if you don't believe me):
Everyone has 2 genes for eye color. Children receive 1 gene for eye color from each parent.
Brown eyes are a dominant trait. One needs only have 1 brown gene to have brown eyes. So [1 brown+1 blue]=brown eyes AND [2 brown]=brown eyes.
Blue eyes are a recessive trait. One must have 2 blue genes to have blue eyes. Again, children get 1 eye-color gene from each parent.
So.
Two blue-eyed people will ALWAYS have blue-eyed children because both people have all blue genes. It is impossible for their offspring to have any
other color eyes.
A brown-eyed person with [2 brown genes] and a blue-eyed person will always have brown-eyed children, because the children will get 1 brown gene from
the brown-eyed parent and 1 blue gene from the blue-eyed parent and [1brown+1 blue]=brown eyes.
A brown-eyed person with [1 brown/1blue] gene and a blue-eyed person can have children with eyes of either color. They have a 50/50 chance of having
blue-eyed kids because the children will get 1 blue gene from the blue-eyed parent, but may get brown OR blue from the other parent.
2 brown-eyed people who BOTH have [1 brown/1blue] can have blue-eyed children, because the kids can get either 2 brown genes, [1 brown/1 blue], or 2
blue genes. They have a 1:4 chance of having blue-eyed children and a 3:4 chance of having brown.
2 brown-eyed people who both have 2 brown genes can ONLY have brown-eyed kids, because they will receive a brown gene from both parents.
