Siblings Ethnicity

Genetic genealogy is the application of genetics to traditional genealogy. Genetic genealogy involves the use of genealogical DNA testing to determine the level and type of the genetic relationship between individuals.
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darkerhorse
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Siblings Ethnicity

Post by darkerhorse »

Can siblings have significantly different ethnic percentages in their DNA?

For example, if the siblings' father is 100% Italian and their mother is 0% Italian, you'd expect each sibling to be 50% Italian, since each parent contributes 50% of DNA.

But, could one sibling have significantly more Italian DNA, say 75% and another significantly less, say 25%, or would they both have to have 50%?

Has anyone had a DNA test where ethnic percentages are significantly different than a sibling's ethnic percentages?

I suspect it's possible.
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MarcuccioV
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Re: Siblings Ethnicity

Post by MarcuccioV »

Since every human has 23 pairs of chromosomes (23 from each parent), each child has half DNA of each parent, but not necessarily the SAME half. If one parent is 100% Italian and the other 100% Irish, for example, each child would get 50% of each. But say one parent is 50% Italian and 50% Greek, and the other parent 50% Irish and 50% German, both siblings COULD have different percentages of each, but still 50% Italian/Greek and 50% Irish/German. At least that's how I understand it.
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SelmaAdam
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Re: Siblings Ethnicity

Post by SelmaAdam »

There something funny to do with DNA shuffle.
Siblings Can Have Surprisingly Different DNA Ancestry. When it comes to tracing your roots through your genes, biological siblings may have less in common than many people expect. Learning how your family ancestry is connected to the human origin journey will help the study.
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MarcuccioV
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Re: Siblings Ethnicity

Post by MarcuccioV »

SelmaAdam wrote: 17 May 2021, 14:22 There something funny to do with DNA shuffle.
Siblings Can Have Surprisingly Different DNA Ancestry. When it comes to tracing your roots through your genes, biological siblings may have less in common than many people expect. Learning how your family ancestry is connected to the human origin journey will help the study.
In the case here, siblings of the same parents both get 50% from each parent -- the variations comes in by what % of the grandparents (and previous generations) DNA is passed down through the parents.

In the example, both siblings would be 50% Italian, but percentages will vary between siblings based on what portions of DNA they get from the prior generations. That's where the random replication comes in to play...
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joetucciarone
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Re: Siblings Ethnicity

Post by joetucciarone »

My two kids (both from me & my only wife), and two of my siblings (we share the same parents) all took Ancestry's DNA test. Ancestry.com's analysis says my two kids each inherited "50% shared DNA" from me. The number of centimorgans they share with me differ slightly: 3,418 and 3,411. Ancestry.com says me and my two siblings have "49% - 56% shared DNA" and the centimorgans numbers I share with them are 2,748 and 2,727. If we're ordinary people, then there's a small amount of randomness involved in the sharing of DNA among siblings, and children.
darkerhorse
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Re: Siblings Ethnicity

Post by darkerhorse »

I think the variation from 50% is more likely due to "statistical error" in DNA testing estimates rather than actual differences.
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MarcuccioV
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Re: Siblings Ethnicity

Post by MarcuccioV »

darkerhorse wrote: 21 May 2021, 18:31 I think the variation from 50% is more likely due to "statistical error" in DNA testing estimates rather than actual differences.
Hai ragione.
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