What is the probablility of a child with dark brown eyes?

[Pure_instinct]

I am skeptical about the reports that blue eyed parents can, rarely, have a child with dark brown eyes. I have yet to see any information on the statistical probability of this. The absence of this information only feeds my skepticism as to the motives behind this recent discovery.

This thread need not argue about whether the research is or is not true.

[Lily]

Blue eyed parents can only have blue eyed children.

[Zubenelgenubi]

I found this, but I don't know that it is up to date:

http://www.docshop.com/assets/images/baby_eye_color_odds.png
http://www.docshop.com/2008/01/04/what-color-will-my-babys-eyes-be/

[1-800]

The main determinant of eye color is the OCA2 gene on chromosome 15. Fitness increments of almost all alleles occur in an epistatic (i.e., interaction among several loci) fashion, instead of a single locus serving as the sole arbiter of phenotype.

Depending on the 'strength' of the blue-eyed parents' OCA2 genes, brown (but more likely green) eyes may be expressed. There are other genes that influence this as well: depending on their relative strengths, even if both copies of the OCA2 gene are fairly strong, brown eyes may still be expressed. Recombination as the gametes are formed may lead to brown eyes. Environmental factors may also lead to brown eyes.

It is rare, however -- certainly less than 1% of the time.

The chart above is accurate, although I disagree that two blue eye parents having a brown-eyed child is an impossibility: just very, very rare.

[Vasily Zaitsev]

I found this, but I don't know that it is up to date:

http://www.docshop.com/assets/images/baby_eye_color_odds.png
http://www.docshop.com/2008/01/04/what-color-will-my-babys-eyes-be/

Assuming the quoted chart is accurate, I now have fewer reservations about breeding with my girlfriend.

[1-800]

More useful would be a DocShop 'What race will be my child be?' complete with a fun little scoring card

Thus

English + Chinese = Tea Gook

German + Italian = Deutschland Dago

Croatian + Serbian = a rape

etc

[Zubenelgenubi]

The chart above is accurate, although I disagree that two blue eye parents having a brown-eyed child is an impossibility: just very, very rare.

True, although if the chart was up to date it would likely indicate <1% as it does for brown resulting for two greens instead of 0%.

[Pure_instinct]

True, although if the chart was up to date it would likely indicate <1% as it does for brown resulting for two greens instead of 0%.

Maybe the probability is so low that it has never yet happened.

[Ahknaton]

Suppose two pairs of all-blue-eyed parents each have a child, producing two green eyed children, (which is possible according to the chart, but with 1 in 10,000 odds). Then these children could grow up and have a brown-eyed child together (<1% chance). That would mean you can get a brown-eyed child from 4 blue-eyed grandparents in two generations. It's not a stretch to imagine it's possible in one.

[Pure_instinct]

Suppose two pairs of all-blue-eyed parents each have a child, producing two green eyed children, (which is possible according to the chart, but with 1 in 10,000 odds). Then these children could grow up and have a brown-eyed child together (<1% chance). That would mean you can get a brown-eyed child from 4 blue-eyed grandparents in two generations. It's not a stretch to imagine it's possible in one.

Since <1% means less than one per cent, that could the most astronomically improbable odds calculable. Yes it would still mean that you "can get a brown-eyed child from 4 blue-eyed grandparents in two generations" in the same way that you can get an asteroid hitting you on the head two seconds after reading this sentence. It's possible.

[Helios Panoptes]

Since <1% means less than one per cent, that could the most astronomically improbable odds calculable. Yes it would still mean that you "can get a brown-eyed child from 4 blue-eyed grandparents in two generations" in the same way that you can get an asteroid hitting you on the head two seconds after reading this sentence. It's possible.

Bizarre post. You make it sound like if an event happens in under 1% of trials, that means it's almost as if it can't happen. Down Syndrome occurs in .1% of births, yet there are plenty of people who have it. On the other hand, getting hit with an asteroid is .000000{...}%.

[Pure_instinct]

Bizarre post. You make it sound like if an event happens in under 1% of trials, that means it's almost as if it can't happen. Down Syndrome occurs in .1% of births, yet there are plenty of people who have it. On the other hand, getting hit with an asteroid is .000000{...}%.

There weren't any trials involved were there?