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Posted by: Amyjo ( )
Date: September 11, 2018 08:37PM

Each parent?

It would be 50/50 DNA split shared by siblings. And the same percentage shared with each parent?

Would that make 50% between parent & child, and 50/50 shared between siblings? Or can one parent's genes predominate? Notwithstanding recessive genes and all?

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Posted by: Tevai ( )
Date: September 11, 2018 08:42PM

My sense is that any individual conception is basically a grab-bag of miscellaneous hard candies, and every time someone reaches into that bag, they pull out a similar--but also somewhat different--mix.

Every biological child of a given mother and a given father (except for identical twins) is going to get a slightly different mixture, but they all come from that same, premixed, bag.

If I am wrong on this, please correct me. This is one of the subjects I would most like the learn, but actually am a dunce in.



Edited 2 time(s). Last edit at 09/11/2018 09:03PM by Tevai.

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Posted by: Amyjo ( )
Date: September 11, 2018 08:53PM

Thanks for the feedback. :)

I was wondering today returning from my brother's funeral, whether I share as much DNA in common with him as each of his children do by virtue that he and I share the same parents?

Now that I really stop to think about it, it seems implausible since he passed on certain traits to his children I did not inherit from either parent.

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Posted by: elderolddog ( )
Date: September 11, 2018 08:51PM

I don't know much, but what I do know is shakey, at best!

I think you have to back up and understand genes, and the fact that some genes dominate others.

If an ovum with a gene for blue eyes is fertilized by an egg with a gene for brown eyes, the kid is going to have brown eyes.

Which backs us up to mitosis...

Hmmm...

Maybe I should stop with the observation that my one 'Mexican' looking daughter has four kids, three of whom look 'gringo, and one looks full on Latino.

It's interesting stuff!

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Posted by: Amyjo ( )
Date: September 11, 2018 08:58PM

My parents were both natural brunettes when they met and married. Although my dad had gone from a dark auburn red to dark brunette by the time he finished his military service in WWII.

Each of their children was blonde or redheads, with the exception of me. People used to stop my mom on the street to ask if we were each adopted since our complexions were so different. My oldest and youngest brother tied us in since they shared the same hair color and ruddy complexion.



Edited 1 time(s). Last edit at 09/11/2018 09:46PM by Amyjo.

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Posted by: olderelder ( )
Date: September 11, 2018 09:06PM

Right. Half of the DNA comes from one parent and half from the other, but it's not the same mix each time.

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Posted by: SL Cabbie ( )
Date: September 11, 2018 09:12PM

It can be traced to one parent or the other, but what you're speaking about involves probabilities and percentages (which is why the study of genetics includes extensive focus on the "science of probability").

One half of my DNA came from my mother; the other half came from my father. That leaves, in the case of my siblings, the "other half" available from each parent. The percentages will vary--identical twins being the exception, of course--which is why some siblings "look very much alike," while at other times there will be clearly obvious differences. My brother, for example, is the only one in our family with my mother's brown hair; the rest of us are blond, or "blonde" in the case of my sisters.

So the answer to your question is "No."



Edited 1 time(s). Last edit at 09/12/2018 01:34PM by SL Cabbie.

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Posted by: ificouldhietokolob ( )
Date: September 11, 2018 09:14PM

Yep, the wise cabbie nailed the math :)

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Posted by: [|] ( )
Date: September 11, 2018 09:30PM

It is true that a child gets 50% of their chromosomes from each parent (excluding X and Y, and excluding nondisjunctions - think Trisomy 21 for example). So each child gets 50% of their DNA from each parent.

It is not true that each child will get the same set of genes. Each parent has 2 copies of each chromsomsome. Say the father has one chromsome with the allele (gene) variant of "A" and one chromosome with the allele "a". During spermatogenesis, each cell undergoes meiotic divisions. (https://en.wikipedia.org/wiki/Meiosis)
As part of that process, each spermatozoa receives only one copy of each chromosome - either "A" or "a" in this example. So one child may receive "A", and another child may receive "a". This occurs for every gene, and the same process happens in every ovum as well. This is somewhat of a random process.

It is also complicated by the process of recombination in which some DNA is transferred between homologous chromosomes so that the chromosome that is transferred to the sperm/ovum may not be identical to the corresponding chromosome of the parent (discussed in above link). This process also is somewhat random.

The result is that siblings will not all get the same collection of genes. Only identical twins will have an identical selection of genes.

When you start looking at phenotypes which result from the expression of genes, it gets much more complicated as it involves dominant, recessive, co-dominant genes, the potential interaction of different genes, and especially epigenetic factors.

Hope that isn't too technical to understand.

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Posted by: Nightingale ( )
Date: September 11, 2018 10:18PM

I'm hopeless at math. I will have to re-read the explanations to refresh my memory on this basic of life. I get the 50/50 from each parent. I get the mix being different for each child. I get there will be some similarities between sibs - that seems obvious. I like Tevai's visual of the grab bag. I wish I had picked up some different candies though!

My parents had five kids. The two eldest had Mom's hair colour, the three younger had Dad's colour. My sibs and I resemble each other but don't really look alike. We all got the blue or green eyes from a double dose of UK parents. And the Viking hair in the case of the youngers. Most of us seem to have grabbed a bigger candy from Dad's side re temperament, especially the two males. That's the way in which we resemble each other the most. I am a lot more like my quieter, gentler mom, older sister and younger brothers fiery like Dad.

Interestingly though, out of my three nieces, two look very much like me, same hair and eye colour and similar voices even. When I (misguidedly) took one little niece and nephew to a (not)Mormon Church picnic once, the RM ward missionary who was "looking after" me as a fresh convert (teaching me the new member class; I was the only attendee, lol), stared at my niece for a moment and said "Nightingale!" in a shocked tone. Like he thought I had had a daughter while in the state of being single. I laughed.

So. Genes. Interesting little candies they are. Skipping one, settling on another. Luck of the draw. In high school once we were (largely unhelpfully) pointing out each other's best feature. My classmates dubbed me the one with the best nose. (That doesn't say much for the noses on the rest of them, haha). My second best feature was nails, third toes. I was disappointed and upset for a long time. I didn't care about nails. I wanted the best eyes or lips or legs - especially legs. I would have liked to hand back my well-aligned toes for something of more import and certainly more prominent. Like blonde hair. I longed to be blonde.

Then I grew up. And it's not necessarily true that blondes have more fun. So there. :)

AmyJo, I guess you're happy to be on your way home. Sorry again for the loss of your brother. The aftermath is always so tough, getting through the funeral etc. They do say that the worst in family dynamics comes out at funerals. The exact wrong time for it. I hope your travel at least is as pleasant as possible.

What are you thinking re your DNA share from the family pot?

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Posted by: Amyjo ( )
Date: September 12, 2018 10:52PM

Nightingale Wrote:
-------------------------------------------------------
> I'm hopeless at math. I will have to re-read the
> explanations to refresh my memory on this basic of
> life. I get the 50/50 from each parent. I get the
> mix being different for each child. I get there
> will be some similarities between sibs - that
> seems obvious. I like Tevai's visual of the grab
> bag. I wish I had picked up some different candies
> though!

That is a good visual to remember. It was a grab bag not of my choosing, but as I've aged have come to accept that I am who I was meant to be in God's handiwork.

>
> My parents had five kids. The two eldest had Mom's
> hair colour, the three younger had Dad's colour.
> My sibs and I resemble each other but don't really
> look alike. We all got the blue or green eyes from
> a double dose of UK parents. And the Viking hair
> in the case of the youngers. Most of us seem to
> have grabbed a bigger candy from Dad's side re
> temperament, especially the two males. That's the
> way in which we resemble each other the most. I am
> a lot more like my quieter, gentler mom, older
> sister and younger brothers fiery like Dad.

I turned out more like my dad in temperament somewhat. But again, as I got older, was able to see personality traits of my mum's I didn't know I had at first. As for my siblings, we're about as different as night and day.

>
> Interestingly though, out of my three nieces, two
> look very much like me, same hair and eye colour
> and similar voices even. When I (misguidedly) took
> one little niece and nephew to a (not)Mormon
> Church picnic once, the RM ward missionary who was
> "looking after" me as a fresh convert (teaching me
> the new member class; I was the only attendee,
> lol), stared at my niece for a moment and said
> "Nightingale!" in a shocked tone. Like he thought
> I had had a daughter while in the state of being
> single. I laughed.
>
> So. Genes. Interesting little candies they are.
> Skipping one, settling on another. Luck of the
> draw. In high school once we were (largely
> unhelpfully) pointing out each other's best
> feature. My classmates dubbed me the one with the
> best nose. (That doesn't say much for the noses on
> the rest of them, haha). My second best feature
> was nails, third toes. I was disappointed and
> upset for a long time. I didn't care about nails.
> I wanted the best eyes or lips or legs -
> especially legs. I would have liked to hand back
> my well-aligned toes for something of more import
> and certainly more prominent. Like blonde hair. I
> longed to be blonde.
>
> Then I grew up. And it's not necessarily true that
> blondes have more fun. So there. :)

Agree with that assessment!

>
> AmyJo, I guess you're happy to be on your way
> home. Sorry again for the loss of your brother.
> The aftermath is always so tough, getting through
> the funeral etc. They do say that the worst in
> family dynamics comes out at funerals. The exact
> wrong time for it. I hope your travel at least is
> as pleasant as possible.
>
> What are you thinking re your DNA share from the
> family pot?

I am the only one in my immediate family to try and revive the Jewish family branch of our Jewish family tree. I believe that I picked up the most Jewish traits out of my siblings. My dad had no Ashkenazi Jewish in him that I know of, but he was as smart as many of them I've met. He could've been Jewish in another life. The four siblings that grew to adulthood, two remained TBM all their lives. Only myself and another sibling have left the cult. Both of us resigning. It was interesting for me to learn some of my Mormon pioneer ancestors left the church later in life. Which was out of the norm for most of the early LDS. Don't know why, but was glad they were able to question enough to figure things out for themselves rather than drinking the Mormon kool-aid.

Being mostly European in my ancestry, was pleasantly surprised to learn I am .1% native American Indian per my DNA. My Indian ancestor dates back app 400 years into the Wayback Machine. That was neat to find out. :)

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Posted by: Void K. Packer ( )
Date: September 11, 2018 10:30PM

On _average_ siblings share 50% of alleles. Depending on the vagaries of recombination, however, the actual amount shared varies bell curve-like from roughly 40-60%, depending where one chooses the sigma cutoffs.

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Posted by: elderolddog ( )
Date: September 11, 2018 10:33PM

> depending where one chooses the sigma cutoffs.


Two inches above the knee, cuz I have decent thigh muscle definition.

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Posted by: Void K. Packer ( )
Date: September 12, 2018 11:19AM

Much too modest, perro viejo. Definition like that requires short short cutoff levis. Think 70s, and I don't mean the defunct cult office. It'll make Saucie wild with desire. <sage nod>

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Posted by: labybug not logged in ( )
Date: September 12, 2018 10:57AM

I was a bone marrow transplant coordinator at a childrens hospital up to a couple months ago. [I](above) has a comprehensive answer for sure. When we haplotype family members for possibble bone marrow donors we look at which sibling are an exact match (and occassoionally we will have a parent that is a match).

Mom and dad have 2 sets of chromosomes which they got from their parents, one set from mom and one set from dad.Moms could look like this

Mom
set 1: asdfg (not reported this way but trying to simplify.
set 2 :werty

Dad:
Set 1 poiuy
Set 2:lkjhg

Child (susie) one can get a set from mom and and dad that looks like this:

asdfg
lkjhg
one set from both parents

Sam could get a set like this:
asdfg
poiuy

Susie and Sam would be a half match even though they have the same parents.

Sara could have this set
werty
poiuy

Sara would be a complete mismatch from Susie, but still a half match to Sam.

If you play it out there could be lots of different combinations. In general, each sibling has a 25% chance of being a match with another. However, I have seen familes where there are 3-4 sibling that all match each other and families with 4 sibs who all have a different combo.

Other factors come into play when it comes to color of hair, eyes, personalities. Logic would be that the siblings most alike share the most common DNA, but this is not the case. There is no way to predict outside of testing.
Hope this is helpful?

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Posted by: cl2 ( )
Date: September 12, 2018 11:43AM

None of us do!?! If we didn't look so much like them in other ways! We all had blonde as children (my dad did, too), but all of us have brown hair now, some darker than others.

I wish my just older sister didn't have so many of the same genes for looks as I do. They always thought we were twins and got our names mixed up. I never wanted to be anything like her. We both worked at the local hospital at the same time for a few years and one of the other workers said we even had the same expressions. That wasn't a compliment!

The thing for me that is so uncanny is how my youngest brother looks so much like my dad--almost a spitting image. Thing is he has half my dad's temperament and half my mom's, which were very different!

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Posted by: angela ( )
Date: September 12, 2018 12:48PM

I don't know the science behind all of it but this I do know.

My sister and I certainly look a great deal a like. It's clear we are sisters.

BUT, personality, temperament, etc., we are on opposite ends of the spectrum in many traits.

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Posted by: lisadee ( )
Date: September 12, 2018 06:49PM

I don't know the answers to this question. But I have seen double 1st cousins look more alike than with their own siblings.... I know a family in which 2 brothers married 2 sisters and their respective daughters, who are double 1st cousins, look more like sisters than cousins....more so than with their actual respective siaters.

Genetics is a mixed bag that can and will draw from any ancestor trait(s).

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Posted by: lisadee ( )
Date: September 12, 2018 07:05PM

Funny story....An older friend once told me how her daughter was born with grey eyes. Neither she nor her husband had that eye color. After viewing the baby, my friend's sister waited until a private moment to ask her, "Whose baby is that? I'm your sister. You can tell and trust me. I won't tell a soul."
My friend said she cried and screamed at her sister that the baby WAS her husband's child and how dare she think otherwise.
The next week after mother and baby were back home, other family members came to visit (1st grandchild). One older relative was her hhusband's GREAT-aunt. She looked at the baby and said, "Oh! She's got eyes just like great-aunt X!"
That was HER great-aunt she was speaking of. So, the grey eyes mystery was solved.

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Posted by: Amyjo ( )
Date: September 12, 2018 11:00PM

My dad's parents children were double first cousins to grandma and grandpa's siblings children. Grandpa's sister married Grandma's brother. Their children grew up together.

The cousin I stayed with during brother's funeral is a descendant of them, as I am. Her mother is my first cousin. She and I are closer in age, and she is my cousin once removed. We are more like sisters than ever. We don't look as much alike as we are alike in some of our mannerisms.

When we were together she told me I do things a lot like her mother does, my first cousin. Funny.

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Posted by: SusieQ#1 ( )
Date: September 12, 2018 09:49PM

I found this article very helpful.

DNA is Like a Bunch of Colored Beads

DNA isn’t passed down from generation to generation in a single block. Not every child gets the same 50% of mom’s DNA and 50% of dad’s DNA. (Unless of course they are identical twins).

This has consequences in terms of how much DNA siblings share. And even more significantly, what DNA they share.

One way to think about this is to imagine DNA as a bunch of colored beads. Since we are interested in ancestry here, we will say that different colors mean different ancestries.

Imagine that a man from Japan marries a woman from Europe. Her DNA happens to be 100% European and his 100% Asian.

Let’s say that the European beads are red and the Asian beads are blue. Here is what this might look like:


https://genetics.thetech.org/ask-a-geneticist/same-parents-different-ancestry



Edited 1 time(s). Last edit at 09/12/2018 09:50PM by SusieQ#1.

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Posted by: olderelder ( )
Date: September 12, 2018 10:00PM

It's also like dealing playing cards from two decks (that were each created from two decks, which were each created from two decks and so on). The two decks get shuffled and the cards get dealt. The possible variations from each shuffle and deal are huge.

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Posted by: Amyjo ( )
Date: September 12, 2018 10:55PM

Well that's an interesting chart!

:)

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Posted by: auntsukey ( )
Date: September 13, 2018 09:26AM

According to Richard Dawkins,"The Selfish Gene", the shared genes are as Amyjo suggested in the first post.

On average, one shares the same proportion of genes with one's parents as with a sibling.

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Posted by: Amyjo ( )
Date: September 13, 2018 10:18AM

Thank you for sharing that!

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Posted by: elderolddog ( )
Date: September 13, 2018 09:37AM

I think you've insulted Richard Dawkins!

That genes are being shared on a 50/50 basis from the parents to the kids, but which genes are dominant us what counts and explains why the parents' kids all look different.

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Posted by: auntsukey ( )
Date: September 13, 2018 09:41PM

Please reread Chapter 6 in "The Selfish Gene" and then explain to me how I have insulted Richard Dawkins.

Dawkins presents a mathmatical/probability model for how much shared DNA there is between parent and child, between siblings, and between cousins, etc. No one is arguing about which inherited genes are dominant. We all know the dominant genes are dominant.



Edited 1 time(s). Last edit at 09/13/2018 09:43PM by auntsukey.

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Posted by: ificouldhietokolob ( )
Date: September 13, 2018 09:44PM

Yes.
But as you wrote above:

"On average, one shares the same proportion of genes with one's parents as with a sibling."

The proportion you share is a different question from WHICH genes you share.

My brother and I each got 50% of our genes from each parent.
We have the same proportion of genes from each parent.

My 50% from dad doesn't match up to his 50% from dad, though. The genes in our proportions are quite different.

Make sense?

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Posted by: elderolddog ( )
Date: September 13, 2018 10:40PM

> Please reread Chapter 6 in "The Selfish Gene"
> and then explain to me how I have insulted
> Richard Dawkins.

Dear Auntsukey,

I have no doubt that Mr. Dawkins properly expressed himself. My jibe was based on MY notion that you stating that he agreed with Amyjo was the insult. While I have not read the passage you are referring to, I feel certain that what I pointed out and what Hie confirmed is supported by Mr. Dawkins. You having him 'agree' with Amyjo is where the 'insult' comes in.

If every child got the same 50/50 from their parents, they would all be identical twins. And such is not the case.

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Posted by: auntsukey ( )
Date: September 13, 2018 11:13PM

Allow me to correct myself.

According to Richard Dawkins,"The Selfish Gene", the shared (DNA*) [is] as Amyjo suggested in the first post.

On average, one shares the same proportion of (DNA)* with one's parents as with a sibling.

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Posted by: elderolddog ( )
Date: September 13, 2018 11:29PM

I’m thinking he was leading up to an important point. It’s my opinion that the statement he and Amyjo agree on is not an important point because it does not deal with the real issue: how and why we are not clones, sharing the same 50/50 blend of parental DNA.

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Posted by: auntsukey ( )
Date: September 13, 2018 11:48PM

In this case he wasn't speaking of dominant or recessive genes, although he discussed that earlier.

Basically, Dawkins was trying to explain altruism. If one shares half of his/her DNA with a sibling, then, according to his 'selfish' gene theory, it is in the interest of a "gene survival machine" (his term for an accumulation of genes acting together e.g., a human being) to act on behalf of a sibling or child in order for the genes to survive.

I'm in over my head but I stand by Amyjo's original post.

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