Why do people say that dark hair and eyes are almost always dominant when they're not?

My sister has dark brown hair and brown eyes. Her husband has light blonde hair and blue eyes. They have 3 kids and 2 of them are very blonde with blue eyes and the other one has red hair and green/blue eyes. We have some blondes in our family but no redheads. I don't understand why the redhead gene is so weak if it appears unexpectedly?

Why do people say that dark hair and eyes are almost always dominant when they're not?

most of the time dark feature is dominant. Nobody said all the time. You have to get into genetics to understand why redheads are a weaker gene, and writing about it would take to much bandwith.

Why do people say that dark hair and eyes are almost always dominant when they're not?

Your sister is carrying a recessive blond gene and a recessive blue eye gene, and the husband may have a red hair gene. Sometimes a red haired child will turn into brown hair later as well.

Eye and hair color seems to never be a sure thing, but it is true that dark hair and eyes are almost always dominant.

Why do people say that dark hair and eyes are almost always dominant when they're not?

Brown hair is a dominant trait, but your sister must be carrying the recessive blue-eye trait and the recessive Blonde hair trait. If so then the chances of having a blue-eyed or blonde haired child is 50/50. It is a little confusing and I didn't understand until I took college biology and a forensics course.

Why do people say that dark hair and eyes are almost always dominant when they're not?

perhaps you should have paid a little more attention in biology class when they were discussing genes. (things like mendels theory of inheritance patterns.)

lets same A- is dark hair a- is light hair

for ex: possible events: sperm (A) meets egg (A)

sperm (A) meets egg (a)

sperm (a) meets egg (A)

sperm (a) meets egg (a)

probable outcomes:

AA Dominant genes- child with Dark hair

Aa- with a dominant trait the child is going to have the dom. trait. so dark hair

aA-

aa- both recessive genes- child with light hair

Why do people say that dark hair and eyes are almost always dominant when they're not?

Blue, green eyes and blonde hair are recessive genes. Brown eyes and brown hair are dominant genes. Check out this site for a full listing of recessive and dominant traits.

http://www.blinn.edu/socialscience/LDTho...

"Recessive gene. Genes are either dominant or recessive. A dominant gene's characteristics will predominate when paired with a recessive gene. For a recessive gene to show, it must be paired with another recessive gene. For example, in humans, blue eyes are recessive and brown eyes are dominant; thus, a person who has blue eyes must have received the recessive blue eye gene from each parent. Of interest perhaps, two blue-eyed parents can have only a blue eyed child; two brown- eyed parents can have either a blue or brown-eyed child."

Why do people say that dark hair and eyes are almost always dominant when they're not?

You have to understand genetics in order to understand this one. A person with brown eyes can have a recessive gene for blue eyes (represented as Aa), so the blue eye gene can get carried along for generations without appearing. If that person with Aa marries another person with Aa (which is the most probable combination) than they have a 3/4 chance of having a brown-eyed baby and a 1/4 chance of having a blue eyed baby.

The red-heair gene, just like the green eye gene, is a genetic mutation. In these cases the gene for blue eyes or for blonde hair becomes mutated and changes into green eyes and red hair. If enough people with these "mutations" (i put it in quotes because it's not like it's a bad thing or anything) have children together the gene can be passed on through generations. It can be visable (dominant, such as in the case of many irish people, like my husband) thoughut each generation, or it can become hidden because one parent has give the child the dominant gene.

I hope this made sense and cleared up some of your confusion.

Why do people say that dark hair and eyes are almost always dominant when they're not?

I think you misunderstand the meaning of a dominant gene. This is an oversimplified answer, but basically here's how (we think) it works:

There are two genes believed to be responsible for determining eye color. We get one set from our father and one set from our mother.

Let's start with the first gene. Brown eyes are dominant (B) and blue eyes are recessive (b).

There are three possible combinations, and a few likely outcomes:

BB - brown eyes

Bb - brown eyes OR green eyes

bb - blue eyes OR green eyes

You don't actually get a gene for eye color as much as you get a gene that determines how much melanin is in your eyes. B - brown eyes - have more melanin. b - blue eyes - have almost none. If you have Bb, you have too much melanin to have blue eyes. If you have bb, you don't have enough melanin to have dark eyes. Think of melanin as food coloring added to vinegar. If there's just a tiny bit, there's no color change. But the more there is, the more the color must change.

The second gene seems to determine the coin toss - if a Bb will have green eyes or brown; if a bb will have blue eyes or green.

This still doesn't explain hazel eyes, or the rare pair of peepers that appears to be grey or violet. There are theories about modifier genes, and so on, but it's all still research.

So yes, brown eyes are dominant - but that doesn't mean that one brown eyed parent will always have brown-eyed children; in fact, TWO brown eyed parents can have blue eyes kids ... it's just statistically less likely.

Hair color is even more nuanced and less well understood, but it appears to work roughly the same way. Brown is dominant; blonde is recessive. Then there's a second set of genes that influence red hair. So you can be:

BB - brown hair

Bb - brown hair

bb - blonde hair

BUT in every case, if you have the gene for the pigment that causes red hair (pheomelanin), you'll have redder hair - it might be auburn, if you're Bb or BB. You'll only get a true carrot top, I think, if you're bb *and* have the gene for red hair.

It's complicated, and there are a seemingly infinite number of combinations - as your sister's family proves!

Why do people say that dark hair and eyes are almost always dominant when they're not?

I think its just a saying, and only half true. I see what your saying in my family and my friends family's as well! Good point.

Why do people say that dark hair and eyes are almost always dominant when they're not?

Well my dad had dark hair and brown eyes, and 2 out of 3 of us had blonde hair and blue eyes like my mom, the other 1 had dark hair but green eyes.

My husband has dark hair and brown eyes (Italian) and both my girls are blonde and blue/green eyes so go figure, but they did get their dads ability to tan.