How can two brown eyed parents have a blue eyed kid?

Question

correct me please if im wrong


but im pretty sure tom cruise and katie holmes both have brown eyes?

how can they have a blue eyed kid when brown eyes are a dominant gene?

oo yeah duh!


know i realized

thank youu

now********

Answer 1

This occurs when both parents have blue eyes as a recessive gene.

Let's assume that "B" means Brown eyes and "b" means Blue eyes. We can put those two b's together into four different pairs: B/B, B/b, b/B, and b/b. Because brown eyes are a dominant gene, any time you see a "B" in an above pair the outcome (what color eyes we see on the person) will be Brown eyes. The only one of the four pairs to result in blue eyes is b/b were there is no brown gene present.

So let's talk about how two parents with brown eyes get a child with blue eyes. When we factor out the possiblities that may occur when two people have a child we have to put together two of the above pairs (this is assuming that we're only dealing with brown and blue traits - let's keep this sort of simple folks!!!). This will always result in four possible outcomes.

If a B/B man has a child with a B/b woman, we have to do four steps. The man's first trait (here a B) paired with the woman's first trait (here a B), which would be B/B. The man's first trait (a B) paired with the woman's second trait (here a b), which would be B/b. The man's second trait (B) paired with the woman's first trait (B), which is B/B. And finally the man's second trait (B) paired with the woman's second trait (b), which is B/b.

This gives us four possible outcomes of B/B, B/b, B/B, and B/b. These parents would have no chance of a blue-eyed child because each of the four pairs has a brown eyed trait present.

Now if a B/b man has a child with a B/b woman, we get the four outcomes of B/B, B/b, b/B, and b/b. That last one (b/b) would be a blue-eyed child. That means that the parents have a one in four chance of having a blue-eyed child.

So....either Tom Cruise and Katie Holmes are BOTH B/b's or the tabloids are right and their child was either adopted or created in some secret Scientology laboratory!!!

Hope this helps!

Answer 2

Because of this.

Brown eyes ae a dominant gene, so if Xx was pure brown eyes, and Yy was pure Blue eyes, an Xy child would have brown eyes since brown eyes are dominent.

However, if two people with Xy, having brown eyes, have a child, there is a 25% chance that the child will have blue eyes, since using the square for genetics, there is 25% of a chance that the genes will be Xx, 50% chance that the genes will be Xy like the parents and 25% chance that the genes will be Yy. Since only Yy will give you blue eyes, there is only a 25% chance that the chidl will have blue eyes, but it is still possible.

Being a dominent gene does not mean that it overrules any other gene when it comes to reproduction, it just means it overrules a recessive gene when the genes are combined.

Answer 3

First of all it doesn't matter what color eyes they have they can have purple eyes and the baby could come out with blue eyes. And yes brown is dominant but there are two different type of genes in every one dominant and recessive. If you do your gene chart right if some one has a dominant gene then the recessive gene can also take place. here look at this


Bb
BBBBb
bBbbb

B= brown
b= Blue
And according to the biology rules two recessive genes act like a dominant gene. there is a 20% chance that they will have another baby that has blue eyes

Answer 4

It doesn't matter what color you and your husband's eye and hair color are. It maters more what your parents (the kids grand parents) hair and eye color are. If you understand the concept from Harry Potter of Full Blood wizards and muggles, hair and eye color can work the same way. Here's the classic examples limiting to eye colors (blue and brown, forget about green and others). Let's say 'B' is the brown eyed gene, 'b' is the blue eyed gene. You get one from your mother and one from your father, and you pass one on to your children (they get the 2nd from your husband). So there are 4 combinations of these genes: BB, Bb, bB, and bb. Only if you have bb will your eyes be blue, because brown is a dominate gene. So if your parents were BB and bb, you would be Bb or bB (brown eyes either way). If your husband's parents were the same way, he would have brown eye too. But that means each of you might pass a B or a b gene to your children. If a child gets both b genes from you , he will have blue eyes even though your eyes are brown. In this setup, the odds of your child having blue eyes is 25%. Of course nature is a little more complex that this simple example, so your odds might not exactly match.

Answer 5

They can have a blue-eyed kid precisely because brown eyes is the dominant gene.

For each non sex-linked gene, a person inherits two copies: one from their mother and one from their father. If the two copies (called alleles) are different, the dominant allele wins out. Dominant alleles are represented by capital letters while recessive alleles are represented with lowercase letters. So someone with brown eyes could be BB (homozygous dominant, that is possessing two brown eye alleles) or Bb (heterozygoues with one brown and one blue allele). So if both parents are heterozygous (Bb) they can each pass a b allele to the offspring. If both parents do so, the child will have blue eyes, having received the genotype bb. This is of course rarer than receiving brown eyes (it's only a 25% chance) but still quite possible.

Of course, eye color is more complex than a single gene, but that's the basics of it.

Answer 6

honey its further down the line of genes you have to look at the whole family it could be brown eyes people for a few generations and blue has been in there somehwere, the two direct parents are not the dominant gene its the family when it comes to eyes and hair color or skin or whatever pay attention in class or pick up one topic related sorry but most people know that come on, Kim

Answer 7

I thought Tom Cruise had blue eyes. Maybe not. Hasn't Katie gushed about the fact that their creepy little kid "looks SO much like Tom" and that she got his eyes?

The kid DOES look like Tom, which is creepy in and of itself.

Answer 8

Genetically, it is possible. If Katie or Tom's parents or grandparents have blue eyes, then it can be passed down to the offspring of their immediate blood line.

Answer 9

if they both carry a recessive gene for blue eyes, the baby has a 1 in 4 chance of having blue eyes. The combinations would be: BB, Bb, Bb, and bb,

Answer 10

If they both have a recessive blue gene they can have a kid with blue eyes