How do two green eyed people have brown eyed children?

Question

The oversimplified explanations of eye colour I've heard have always described the brown eye 'gene' as being dominant...clearly not in my family!
If it helps the only person with brown eyes in my family is a great uncle on my dad's side.

I do know a fair amount about biology (just not complex genetics) so don't be afraid to make it complex and point me towards papers in PRJs and so on.

As I said, I do know a bit about biology so I understand Mendelian inheritance...clearly that's not the issue in this case.
I'm also fairly confident that my parents are who I think they are, unless my mother was carrying on an affair with the same milkman in two different parts of the country.

Thanks Helene_thygesen and steve-bob

Answer 1

Presumably, your parents lack two different parts of the pigment pathway. Suppose the two genes A and B are both needed to produce the brown pigment. They are both dominant so one copy is enough. Your father could be AAbb and you mother aaBB. If that's the case, your father would be blue-eyed because he has no B-gene and you mother because she has no A-gene. All children would be AaBb and thus brown-eyed.

If your father is Aabb and/or if your mother is aaBn, they could get both blue- and brown-eyed children.

Answer 2

It's completely possible genetically, and is called genetic throwback.

The model of two genes for eye colour is a very simplistic one, which is used to introduce the concept of genetic inheritence. There are however many more genes which contribute to the eye colour. It is therefore possible that both your parents have parts of the brown eye genes, but not enough to make a full brown eye, and the bits from each parent add up to a whole brown eye (see someones AAbb and aaBB explanation above).

So the main thing to remember: genetics isn't quite so simple as everyone has two genes for each characteristic.

Answer 3

If you want a simple answer to this read up on the experiments done on the Sweet Pea done by a chap called Gregor Mendel. He was an amazing Monk who lived centuries before the science of genetics and is generally now regarded as the founder of this subject.

He was the one who found out that some genes for colour and hieght are dominant and devised simple rules and reasons behind it all.

Answer 4

You Can Get your eye color from anyone in your family the only thing that u have to get from your Parents is their Blood Type It has to be one or the others if not someone was Cheating

Answer 5

Genes are random, both parents have the gene in them which could make anything about the child come out different from them both. Darker colors are dominant, so it's very possible that this could happen.

Answer 6

Eye color is one of the few traits that do not follow the rules of Mendelian intheritance. Here's a link if you want to read up on any of it http://en.wikipedia.org/wiki/Mendelian_inheritance

Answer 7

because some one in your past had brown eyes means you carry the gene for it and brown is one of the dominant colours and can reappear at any time

Answer 8

genetics... same as two brown eyed people have green eyed children like myself... yet mine and my husbands parents generation and our grandfathers/grandmothers generation dnt have green eyes onliy hazel... so it goes bak quite a bit!

Answer 9

its genetics , it is always possible. its because there are genes in teh children which carry the genetic information from its grand parents or relatives.

Answer 10

Oh dear, shame and scandal in the family