Someone who knows something about genetics?

Question

I was taught that if two parents both have blue eyes then they cannot reproduce a child with brown eyes however two people with brown eyes can have a child with blue eyes. If one parent has only brown genes (meaning all their ancestors had brown eyes) and the other parent has blue eyes, then the child will have brown eyes. Is this not true?

Answer 1

The first part is true, as blue is a recessive trait and will only express when present in a homozygous state.
but an individual having brown eyes may be heterozygous or homozygous for the trait.
As you said that the parent havin brown eyes ( in the 2nd case),had all the ancestors with brown eyes,probality is more that he is homozygous for the trait.and when a homozygous brown eyed parent is crossed with a blue eyed parent, u'll only get heterozygous brown eyed offsprings.

so its also true.

Answer 2

We're talking about dominant and recessive genes here. In most human populations, the genes for blue eye color are recessive. This means that both of the chromosomes with those genes must have the blue ones to enable the person to have blue eyes. If one of the chromosomes has a dominant gene complex (say for brown eyes), then the person will probably have brown eyes.

In the example you gave, the offspring will have one blue gene set and one brown gene set. Brown being usually dominant, the eyes should be brown. Remember, however, that most genetically determined characteristics are not necessarily the result of one particular gene. Recent discoveries indicate that multiple genes can contribute to a given condition. And there is always the very slim possibility of mutation occurring.

This, of course, is the inspiration for the Crystal Gayle song "Don't It Make My Brown Eyes Blue." And you thought it was about a failed love affair.

Answer 3

blue is a recessive gene and brown is a dominant, which means that more often than not you will have brown eyes. If the mom and the dad have blue eyes, there is a 75% chance that the kid will have blue eyes. That means that the brown dom. is still present and can still overtake that blue res. genes. Now if a parent has blue eyes and the other has brown that drops to 25% chance of blue eyes. and if both parents have brown eyes, it depends on what their genetic makeup is if the kid has any chance at all for blue eyes.

Answer 4

Eye color is much more complicated than that. Eye color depends on many different alleles present on genes. Ideally, what you say is true, but there are so many other factors involved, that this doesn't always happen. Different combinations of alleles bring about different eye color, and the alleles which a parent passes on aren't necessarily shown in the parent's eye color. You cannot have 'only brown genes' brown is a combination of, say, allele a, b, d, x, g, h, and k; but also could be a combination of d, g, u, k; and also a million other things. Blue eye color generally takes less alleles or non-dominant alleles to create, but every case varies. When you study biology though, things tend to be simplified as 'blue' genes and 'brown' genes. For study purposes, what you say is true, but in real life, it's not that simple. I don't think scientists even really know.

Answer 5

Brown eyes is a dominant gene, whereas blue eyes is a recessive trait. And so, it is likely that the brown-eyed parent will be looking into their child's brown eyes. Dark hair is dominant over recessive light hair.

Answer 6

That is not necessarily true. How it works is that both parents have DNA from their parents, and their parents. If either parent has parents or other parents with blue or brown eyes, it is possible, however unlikely. That refers to the dominant gene. In the first part that is what you are talking about.

Answer 7

Here we go again. First - you have to realize - 7th Heaven is a TV show dear. Go to these web sites and take a class in biology and PAY attention.

http://en.wikipedia.org/wiki/Recessive_gene

http://www.accessexcellence.org/RC/VL/GG/recessive.html

http://www.athro.com/evo/gen/eyecols.html

Or - you can go to www.ask.com and type in "recessive genes".

Answer 8

we know A LOT about genetics. what's the question again?

http://www.youtube.com/watch?v=H2jtRWFOd04

http://www.youtube.com/watch?v=A55CzcYl7qQ