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Author Topic:   What all can you find out from DNA anyway?
Coyote
Member (Idle past 55 days)
Posts: 6117
Joined: 01-12-2008


(1)
Message 16 of 28 (787792)
07-21-2016 8:25 PM
Reply to: Message 12 by Faith
07-21-2016 5:34 PM


Re: Errors Changes
I object to the idea that they are normal events that make normal alleles, I object to the idea that they contribute anything genuine to genetic diversity and so on. But there's no reason I should object to their identification of people groups; in fact that's an unexpected benefit from an error.

For tracing ancestry we are not looking at "errors;" we are looking at "changes."

The changes can be good, neutral or bad (but insufficiently bad to kill off the recipient)--it doesn't matter.

Any changes which can be tracked through successive generations can be used for tracking ancestors and descent groups.


Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.

Belief gets in the way of learning--Robert A. Heinlein

In the name of diversity, college student demands to be kept in ignorance of the culture that made diversity a value--StultisTheFool

It's not what we don't know that hurts, it's what we know that ain't so--Will Rogers

If I am entitled to something, someone else is obliged to pay--Jerry Pournelle

If a religion's teachings are true, then it should have nothing to fear from science...--dwise1

"Multiculturalism" demands that the US be tolerant of everything except its own past, culture, traditions, and identity.


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Faith
Member
Posts: 30028
From: Nevada, USA
Joined: 10-06-2001
Member Rating: 1.2


Message 17 of 28 (787798)
07-21-2016 11:18 PM


Of course I wonder how reliable the test is. What if there are people groups that have no identifying mutations?

Or, here's a specific question: the person who was tested has a Jewish ancestor who is half Northern/Eastern European/Ashkenazi and half Sephardic (Portuguese in this case) but the percentage given makes the ancestor about 97% Ashkenazi. Should this be explained as there being no particular Sephardic mutation? So that it's all just Jewish DNA? Or could it mean that the Sephardic ancestors had a lot of Ashkenazi ancestry they didn't know about? (A little odd in this case because they have genealogies that go back to the fifteenth century with Sephardic names). And should that unaccounted for 3% be supposed to come from a nonJewish ancestor? Perhaps even that small South Asian percentage?

Also said person has a grandmother who is French. But the percentage of French in his test is minuscule, like 1.2%. Does that mean the French grandmother doesn't know her real genetic background or what?

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.


Replies to this message:
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Asgara
Member (Idle past 252 days)
Posts: 1783
From: Wisconsin, USA
Joined: 05-10-2003


Message 18 of 28 (787799)
07-22-2016 12:19 AM
Reply to: Message 17 by Faith
07-21-2016 11:18 PM


Each individual receives half their DNA from each parent. You might have a maternal relative that was French but you might not have received any DNA from that line that has the changes necessary for identification.
This message is a reply to:
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Replies to this message:
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NoNukes
Inactive Member


Message 19 of 28 (787801)
07-22-2016 1:11 AM
Reply to: Message 18 by Asgara
07-22-2016 12:19 AM


unneeded comment.

Edited by NoNukes, : No reason given.


Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)

History will have to record that the greatest tragedy of this period of social transition was not the strident clamor of the bad people, but the appalling silence of the good people. Martin Luther King

If there are no stupid questions, then what kind of questions do stupid people ask? Do they get smart just in time to ask questions? Scott Adams


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frako
Member
Posts: 2795
From: slovenija
Joined: 09-04-2010
Member Rating: 3.3


(3)
Message 20 of 28 (787807)
07-22-2016 4:32 AM
Reply to: Message 17 by Faith
07-21-2016 11:18 PM


Or could it mean that the Sephardic ancestors had a lot of Ashkenazi ancestry they didn't know about?

Um could have been the Ashkenazi mailman's fault if you know what i mean.

Edited by frako, : No reason given.


Christianity, One woman's lie about an affair that got seriously out of hand

What are the Christians gonna do to me ..... Forgive me, good luck with that.


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Pressie
Member
Posts: 1911
From: Pretoria, SA
Joined: 06-18-2010


Message 21 of 28 (787809)
07-22-2016 7:21 AM
Reply to: Message 10 by mike the wiz
07-21-2016 4:32 PM


Re: Perhaps a good analogy
Goodness gracious. You love your word salads.
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NoNukes
Inactive Member


(1)
Message 22 of 28 (787860)
07-22-2016 7:04 PM
Reply to: Message 10 by mike the wiz
07-21-2016 4:32 PM


Re: Perhaps a good analogy
I call them, "fictional" because as far as I can tell, I have to imagine these things existed.

You have ancestors that lived during the time that Christ walked the earth, but you don't have any idea of their names, appearances, etc. You can only imagine them. Does that make them fictional? Of course not.


Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)

History will have to record that the greatest tragedy of this period of social transition was not the strident clamor of the bad people, but the appalling silence of the good people. Martin Luther King

If there are no stupid questions, then what kind of questions do stupid people ask? Do they get smart just in time to ask questions? Scott Adams


This message is a reply to:
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Replies to this message:
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ramoss
Member
Posts: 3087
Joined: 08-11-2004


Message 23 of 28 (788021)
07-24-2016 6:50 PM
Reply to: Message 22 by NoNukes
07-22-2016 7:04 PM


Re: Perhaps a good analogy
If you had relatives that lived in Europe at that time period, you are a direct descendant of everyone in Europe that has a direct descendant.

Me, I am descended from Charlemagne

http://phenomena.nationalgeographic.com/...universal-royalty


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Replies to this message:
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NoNukes
Inactive Member


Message 24 of 28 (788024)
07-24-2016 8:13 PM
Reply to: Message 23 by ramoss
07-24-2016 6:50 PM


Re: Perhaps a good analogy
If you had relatives that lived in Europe at that time period, you are a direct descendant of everyone in Europe that has a direct descendant.

Surely this is not the case. You are not a direct descendant of your own siblings regardless of how many children they have. And it is unlikely that you would be the direct descendant of any sibling of your grand parents or your aunts and uncles. Are you sure you are saying what you meant to say here? Is it instead that you are direct descendants of all of those old Europeans from 1 AD?

Edited by NoNukes, : No reason given.


Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)

History will have to record that the greatest tragedy of this period of social transition was not the strident clamor of the bad people, but the appalling silence of the good people. Martin Luther King

If there are no stupid questions, then what kind of questions do stupid people ask? Do they get smart just in time to ask questions? Scott Adams


This message is a reply to:
 Message 23 by ramoss, posted 07-24-2016 6:50 PM ramoss has responded

Replies to this message:
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ramoss
Member
Posts: 3087
Joined: 08-11-2004


Message 25 of 28 (788185)
07-26-2016 6:01 PM
Reply to: Message 24 by NoNukes
07-24-2016 8:13 PM


Re: Perhaps a good analogy
No, you not a direct decendent of your syblings, but your syblings were not alive 1500 years ago either.

'Of that time period' is of 1500 years go.


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Modulous
Member (Idle past 53 days)
Posts: 7789
From: Manchester, UK
Joined: 05-01-2005


Message 26 of 28 (791456)
09-15-2016 1:30 PM
Reply to: Message 17 by Faith
07-21-2016 11:18 PM


Of course I wonder how reliable the test is. What if there are people groups that have no identifying mutations?

Then you wouldn't be able to identify them from the DNA. This is an issue of resolution rather than reliability though. You can't see EVERYTHING from DNA, but that doesn't mean the information you can infer is unreliable.

It is, however, not 100% perfect.

Or, here's a specific question: the person who was tested has a Jewish ancestor who is half Northern/Eastern European/Ashkenazi and half Sephardic (Portuguese in this case) but the percentage given makes the ancestor about 97% Ashkenazi. Should this be explained as there being no particular Sephardic mutation?

Depends on the test, really. The Ashkenazi and Sephardic are very similar, typically coming out as quite close to Southern Europe (Italy, Greece, Spain) , for perhaps obvious reasons. A cheap test such as the 23andme test, only looks at a small selection of genetic markers and as said, the two groups are very similar to one another. Not sure if there is a definitive indicator that separates them but 23andme may simply not check it.

Or could it mean that the Sephardic ancestors had a lot of Ashkenazi ancestry they didn't know about?

From wiki:

quote:

In the case of Ashkenazi and Sephardi Jews (in particular Moroccan Jews), who are closely related, the source of non-Jewish admixture is mainly southern European. Behar and colleagues have remarked on an especially close relationship between Ashkenazi Jews and modern Italians.
...
"Ashkenazic and Sephardic Jews have roughly 30 percent European ancestry, with most of the rest from the Middle East." He further noticed that "The two communities seem very similar to each other genetically, which is unexpected because they have been separated for so long." Concerning this relationship he points to Atzmon's conclusions that "the shared genetic elements suggest that members of any Jewish community are related to one another as closely as are fourth or fifth cousins in a large population, which is about 10 times higher than the relationship between two people chosen at random off the streets of New York City"

. And should that unaccounted for 3% be supposed to come from a nonJewish ancestor?

Well, as an approximation, it probably suggests not that there is *A* non-Jewish ancestor, but that 3% of the ancestors were non-Jewish.

Also said person has a grandmother who is French. But the percentage of French in his test is minuscule, like 1.2%. Does that mean the French grandmother doesn't know her real genetic background or what?

Well said person only inherited about 25% of said grandmother's genes. Said grandmother is unlikely to have 100% northern European genetic markers (because Europe has had a lot of migration to and fro), and is certain to not have only genes that are characteristic of French.


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14174dm
Member
Posts: 136
From: Cincinnati OH
Joined: 10-12-2015


Message 27 of 28 (791458)
09-15-2016 2:39 PM
Reply to: Message 26 by Modulous
09-15-2016 1:30 PM


Question on inheriting
person only inherited about 25% of said grandmother's genes

I was wondering - is the 25% of grandmother's genes an exact number or is it a rough approximation for the whole gene?

Is it physically possible but statistically unlikely that a person could get 50% of genes from maternal grandmother, 30% from paternal grandfather, 15% from maternal grandfather, and 5% from paternal grandmother?

I would assume that the statistics depend on which and how many genes are compared. The more comparisons, the closer to 25% each.


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Modulous
Member (Idle past 53 days)
Posts: 7789
From: Manchester, UK
Joined: 05-01-2005


Message 28 of 28 (791464)
09-15-2016 4:06 PM
Reply to: Message 27 by 14174dm
09-15-2016 2:39 PM


Re: Question on inheriting
I was wondering - is the 25% of grandmother's genes an exact number or is it a rough approximation for the whole gene?

Neither. It's a very close approximation based on the law of large numbers. Genetic recombination is like thousands of coin tosses.

Is it physically possible but statistically unlikely that a person could get 50% of genes from maternal grandmother, 30% from paternal grandfather, 15% from maternal grandfather, and 5% from paternal grandmother?

Absolutely, but I think there are evolved genetic mechanisms that 'enforce' a 50% division so it's not left entirely to chance. There are however, many many complications.

I would assume that the statistics depend on which and how many genes are compared. The more comparisons, the closer to 25% each.

Indeed.


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