When two breeds of animal create an offspring, is the offspring considered 2/3 or 1/2 the mother's breed?

Question

Someone told me of a hunter who shot a bear that was 1/3 polar bear and 2/3 grizzly bear. I said that was impossible for the bear to have been 1/3 anything and 2/3 anything because the bear has TWO parents. So it can only be 1/2 polar bear and 1/2 grizzly bear.

Even if you go back another generation, the bear has 4 grandparents, not 3, so the proportions of grizzly to polar can only be measured with fractions that have denominators of 4.

I told him that if my father were Native American and my mother were Spanish, that would make me 1/2 Native American and 1/2 Spanish. If only my father's father were Native American and my other 3 grandparents were Spanish, that would make me 1/4 Native American and 3/4 Spanish.

I told him you could never be 1/3 anything because no matter how many generations back you go, you can never get a denominator common with three.

There are 2 parents.
There are 4 granparents.
There are 8 great-grandparents.
There are 16 great-great GPs
There are 32 great great great GPs
There are 64 great great great great GPs
and so on, up to 8192 great-great-great-great-great-great-great-great-great-great-great GPs (this is where I stopped counting, but none of these are multiples of 3, and I bet it never reaches a common denominator with 3).

BUT...

This boy said all that didn't matter. He said that because the MOTHER was a grizzly bear and the FATHER was a polar bear, the offspring inherited 2/3 of the mother's genes and only 1/3 of the father's genes, making the offspring 1/3 polar bear and 2/3 grizzly bear.

He said that the mother bear's egg contributes 2/3 of the genetic material, and the father bear's sperm only contributes 1/3 of the genetic material, so that makes the offspring 1/3 polar and 2/3 grizzly.

I NEVER heard anything like that before, and figured that if that were true, there'd be no reason why that wouldn't apply to humans also, since we're also members of the animal kingdom. So that would make anybody with a German mother and an Irish father 2/3 German and only 1/3 Irish, which seems ridiculous to me.

So who's right? Am I right or is this other person right?

Answer 1

In general, you are correct. You inherit exactly 1/2 of your genes from your mother and 1/2 from your father. The boy is incorrect in stating that you inherit more from your mother.

HOWEVER ... it is not so simple when you go back as far as your grandparents. You do not necessarily inherit 1/4 of your genes from each grandparent. If your grandparents have four different ethnicities A, B, C, and D, you are *not* necessarily equal amounts of each. And this has nothing to do with dominant/recessive genes ... purely the NUMBER OF CHROMOSOMES INHERITED FROM EACH GRANDPARENT.

To see this, remember that humans have 46 chromosomes, organized as 23 pairs. The process of creating an egg cell randomly selects one chromosome from each pair so the egg cell has 23 chromosomes. Same with the process of creating a sperm cell, so each sperm cell has 23 chromosomes.

So you did indeed get 23 chromosomes from mom's egg cell, and 23 from dad's sperm cell. So it's exactly 1/2 from each parent.

But look at that egg cell from mom that had 23 chromosomes. Each of those 23 chromosomes originated either in maternal grandma or grandpa. But what distribution between the two? First, it's impossible that these 23 were split equally from grandma and grandpa (because you can't divide 23 evenly).
Instead, any of the following are possible ways (random combinations) that make up those 23 chromosomes in that egg cell from mom:
12 from grandma; 11 from grandpa.
15 from grandma; 8 from grandpa.
20 from grandma; 3 from grandpa.
3 from grandma; 20 from grandpa.
23 from grandma; 0 from grandpa.
0 from grandma; 23 from grandpa.

So it is possible that you got 15 (out of your full 46) chromosomes from your maternal grandmother, and only 8 from your maternal grandfather. In fact it is possible (although extremely unlikely) that you got 23 chromosomes from your grandmother, and 0 from your maternal grandfather.

Now if both your maternal grandparents were Native American, then yes, this would still add up to 1/2 Native American. But if one grandparent was, say, Cherokee and the other Shawnee, then it is *not* necessarily true that you are 1/4 Cherokee. You could have 15 "Cherokee chromosomes" so you would be about 1/3 Cherokee. (15/46 = 1/3, approximately.)

As for your bear example, it is *possible* to have a 1/3 polar bear an 2/3 grizzly ... although not in the way the boy said. How? Well, I don't know how many chromosomes bears have, so lets just say 60 to make the math easier. Imagine the bear's maternal grandmother was a polar bear and the other three grandparents were grizzlies. Then it is possible that it got 20 chromosomes from maternal grandmother (the polar bear), 10 from maternal grandfather (a grizzly), and the remaining 30 chromosomes from his paternal grandparents (both grizzlies). So that means that 20 out of his 60 chromosomes were polar bear, and 40 were grizzly chromosomes. That would make the bear exactly 1/3 polar bear, 2/3 grizzly. So it is *possible*.

Again, that is completely different for how that boy thought it would happen ... and this could probably only be confirmed by genetic testing.

Answer 2

You are right. Half the genes come from the mother, and half from the father. The only exception is the mitochondrial DNA which are coming only from the mother, but do not have control on the physical appearance of an offspring.

That said, you could be "about" 1/3 of something. If, for instance, 5 of your 16 great-great-grandparents were, say, Irish, and the other 11 were not, you would be 5/16 Irish, which is pretty close to 1/3.

But I doubt this is the case with this bear thing.

Answer 3

One half on the genes in the nucleus of mammalian cells comes from the mother and 1/2 from the father, so it would be considered 1/2 of the mother's breed. However, there is a small amount of DNA in the mitochondria of the cells (I don't know if the genes have been identified). Since an egg contains cytoplasm (and hence mitochondria) and a sperm does not, the mother is indeed contributing a TINY amount more DNA (nucleus + mitochondria) than the father contributes, but certainly not 2/3.

Answer 4

Half of our genes come from our mother and half from our father- the egg has one set of chromosomes and the sperm the other. therefore you are right and the person who said 1/3rd is wrong. Now, some traits might be more dominant than others, therefore it may seem as if the person has more from their mother or father, however each parent contributed the same amount of genetic material. When you take biology (if you are a kid, if you aren't a kid and you just don't remember, ask a biology teacher maybe) they will tell you the basics of genetics. there are charts with x and y standing for mother and father genes and such. I don't remember what they are called tho, sorry. Good luck convincing this other person, i'd say just let it go he will find out.

Answer 5

I was trying to see if I could find another way to see where that could be true but i guess i might be wrong but still if you go further, around 4294967296 and up, i guess i could be right but the only way was that if 2863311531 of its ancestors were grizzly bear and 1431655765 were polar bear which would give you 2/3 of grizzly and 1/3 of polar. but i guess that would take you approximately 30,000 years for that to happen. so i guess you are right not to believe.

Answer 6

Are you for genuine? highway doggies have an more suitable mortality cost than doggies born to breeders. affliction, a foul mothers, bigger hazard of being killed by applying yet another person canines, loss of nutrition etc. Immature bitches not often make good mothers. greater healthy? stunning, yeah mange, fleas and different parasites extremely make for greater healthy animals. No they proceed to exist on rubbish and despite the fact that they are able to capture and scavenge. will not be able to even analyze them to WILD canines because maximum wild animals do no longer breed till they seem to be one million or older. formerly that they are nonetheless probable with their start p.c.., that's all appropriate individuals. Oh and as far as Rabies is going - seem to china and the middle east relating to feral canines. The final time those 2 aspects have been interior the information it substitute into because of the fact they have been going out to skinny down the feral canines inhabitants no longer purely for the first threat the proposed to human beings and different animals, yet in addition because of the fact of Rabies cases. Being wild does no longer look after ANY animal from catching rabies.

Answer 7

The bear did inherit half the mother's gene and half its fathers genes because if the egg had only 1/3 of the gene then there would be no fertilisation - let me explain - human beings have these disease called Down's Syndrome which happens because the sperm carry 23chromosomes - the correct amount while the mother's egg carry 24chromosomes. This happens usually if the mother is over 40 year - in which situation the ovulation cannot occur properly. Meiosis - the process of forming eggs does not occur properly and so the egg cells split into pairs of 22/24 instead of 23/23 - which is normal. The eggs carrying 22 chromosomes cannot be fertilised at all by any sperm as it is short of one chromosome. The eggs carrying 24chromosomes gets fertilised and it results in babies who have the DOwn's syndrome. THe children tend to have a very short life expectation because of these abnormality.

Both the eggs and the sperm must contain equal number of chromosomes for the egg to be fertilised. Artificial methods of cross breeding is the only other way you can fertilise eggs and sperms with unequal number of chromosomes.

The case with the bear is that only one-third of the genes from the egg is dominant over the father's genes. For instance in human beings if one parent has black eyes and both her/his parents have black eyes then she have inherited two genes for black eyes and when her cell splits to become egg, both daughter cells will contain a gene containing instructions for black eye formation.

Now, if the father has brown eyes and both his parents had blue and brown eyes then when his cells undergo meiosis then one of his sperm would carry instruction for brown eye formation and the other for blue eye formation - even though he has brown eyes because the gene for brown eye is DOMINANT over the gene for blue eye. So, only one of his parents' characteristics are expressed as both can't be expressed together.

Now when he mates with the girl with the black eye, their children will have black eyes because the gene for black eye is DOMINANT over the gene for brown eyes. The child will still have the information needed for brown eye formation in the cells of his or her body but it would not be expressed as that gene is RECESSIVE.

As you can see from these examples, the bear did inherit half of its mother's chromosomes and half of its father's chromosomes (if it was not bred for experiments using artificial means) but only 1/3 of his mother's chromosomes are dominant over the father's and is expressed. The other half remained recessive and its children may carry its mother's characteristics if it mates with a bear with genes recesive to its mother's genes.

Hope this helps.

Answer 8

It would be 1/2 regardless of the breeds involved; any baby is comprised of half the father's and half the mother's genetic makeup.

Have a great day!

Answer 9

I would go by the 2 most predominant ethnic backgrounds of your ancestors, rounded off to the nearest tenth

But really, assuming you were born in Canada, you would be canadian, with an X and Y background. Breaking humans down into fractions just seems wrong to me.

Answer 10

It's really not that important.

You're not 1/3 or 1/2 anything. You're always 100% you

It's really NOT important.