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Anyone remember the blue/brown eye debate?

(55 Posts)
MamaMaiasaura Sun 12-Jun-05 12:51:58

I remember their was a big discussion and some research as well to say blue eyed parents could have a brown eyed child.. was looking on bbc website and found this which is cool but says that blue is recessive and if you are with Ewan for example who has bb gg both recessive there is no way you can have brown eyed baby as B is dominant. here this

Gobbledigook Sun 12-Jun-05 14:09:54

I don't remember the debate about this but what you have said is right. The gene for blue eyes is recessive, therefore to have blue eyes you must have the blue gene from both parents.

If both parents have blue eyes, then they both have BB therefore the child can only have blue eyes.

edam Sun 12-Jun-05 14:15:56

With my ancient o-level in biology I'd say that's right but like most o-level science it may be an oversimplification - can you have blue eyes but carry a brown-eyed gene and hand that on to your baby? I know that some genes can be inherited but not expressed in that individual but no idea if that is the case with eye colour.

Pah to dominant genes, I was confidentaly expecting a brown-eyed baby like me but got a bluey like dh.

Gwenick Sun 12-Jun-05 14:37:22

If both parents have blue eyes, then they both have BB therefore the child can only have blue eyes.


Really??.............now I'm wondering about the 'parents' of one DS1's best friends!!!

colditz Sun 12-Jun-05 14:38:13

I think you carry a dominant and recessive gene for your eyes. ie If my mum hadgreen and my dad had blue, I carry blue dominant, green recessive. If dp also has blue dominant and green recessive, I think there is a one in 4 chance of baby having green eyes. The possibilities would be BB, Bg, Bg, and gg, the two recessive greens leading to green eyes.

Gwenick Sun 12-Jun-05 14:38:16

Does it work the other way too??

Both my parents (and both sets of grandparents) have/had brown eyes..........but I've got blue ones

hunkermunker Sun 12-Jun-05 14:39:30

What about if you have blue/green/brown/grey eyes? Mine are all of those at different times...

colditz Sun 12-Jun-05 14:40:24

The you most be carrying a dominant awkward gene!

Gwenick Sun 12-Jun-05 14:40:55

Colditz - who me or HM???

hunkermunker Sun 12-Jun-05 14:41:01

Colditz, that has long been suspected

colditz Sun 12-Jun-05 14:41:24

Then Gwenick both of your parents must have had recessive blue genes.

edam Sun 12-Jun-05 14:41:44

Thanks Colditz, that's what I'd vaguely remembered.

colditz Sun 12-Jun-05 14:41:50

Sorry I meant HM has awkward genes

hunkermunker Sun 12-Jun-05 14:42:27

HappyHuggy Sun 12-Jun-05 14:42:40

My eyes are brown and dh's eyes are blue.

our eldest child has brown eyes and our youngest has blue.

am a bit confused now!!!

Gwenick Sun 12-Jun-05 14:43:58

I'm confused (and cr*p at science so please excuse me). So do the recessive genes come down 'through' the generations - ie would both my parents have got recessive blue genes from their parents, who both had brown eyes?????

Gwenick Sun 12-Jun-05 14:44:18

well we always knew that about HM

colditz Sun 12-Jun-05 14:44:37

Happy huggy if you are carrying a recessive blue gene (one that is not expressed because your eyes are brown) Then you can have a blue eyed child.

colditz Sun 12-Jun-05 14:45:20

gwenick, yes, that is what can happen. Hence "throwbacks"

edam Sun 12-Jun-05 14:53:41

When ds's eyes stayed blue I realised I must carry a recessive blue gene although my eyes are brown, my sister's eyes are brown, my mum's are brown and my dad's grey. God knows how blue got in there but it obviously did!

colditz Sun 12-Jun-05 14:56:49

Dp and I both have blue eyes, but both our mothers have green eyes. So if we have another child, there is a one in 4 chance of baby having green eyes!

I had to educate myself on this matter whilst pregnant, as dp is a bit ignorant of such things and not explaining and proving this would have left me open to all sorts of accusations!

MamaMaiasaura Sun 12-Jun-05 15:01:41

basically as i understand it.. it is that b = blue G = green (dominant over blue) and B = brown (dominant over every other gene). So basically if one parent has blue eyes & one has brown on average 50% chance child will have brown eyes, 25 % for blue or for green. However 2 parents with blue eyes (bb or bg - both recessive/no dominant gene - they will have blue eyes) if a parent has green eyes and the other blue then 50/50 chance of blue or green but NO brown..

Gwenick Sun 12-Jun-05 15:03:17

I had to educate myself on this matter whilst pregnant, as dp is a bit ignorant of such things and not explaining and proving this would have left me open to all sorts of accusations!



Well my mum had lots of 'raised' eyebrows when I was blue eyed, with all her family dad's family all having brown eyes. Especially as I was concieved 6 weeks after she had the coil fitted........and while dad was home om shore leave for just 2 weeks

colditz Sun 12-Jun-05 15:04:22

I always thought blue was dominant over green? correct me if I'm wrong... but you don't see many people with green eyes

happymerryberries Sun 12-Jun-05 15:07:10

tamum is the person to ask about this, as she is the genetics expert.

What I do know is that eye and skin colour is not controled by a single gene (regardless of what we teach at GCSE!) So it is more complex than the simple, two blues=blue eyes. Skin tone is controled by at least 4 different genes and that helps to explain the range of skin tones. Eye colour also has more than one gene conroling it and also needs the function of nerevs to allow the pigment to develop, which explains how people can have two different coloured eyes.

What we teach is that brown is dominant over blue.

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