Is It Quantity or Quality at Play?

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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Is It Quantity or Quality at Play?

Post by darkerhorse »

My paternal grandparents were both 100% Italian (Sicilian). My maternal grandfather was 76% Norwegian, 12% Danish, and 12% German. My maternal grandmother was 100% French (Canadian).

Ancestry for my maternal 1st cousins is: paternal grandfather 76% Norwegian, 12% Danish, and 12% German. Paternal grandmother 100% French (Canadian). Maternal grandfather 100% Italian (Northern). Maternal grandmother 100% French (France).

That makes me 50% Sicilian, 25% French-Canadian, 19% Norwegian, 3% Danish, and 3% German, and my cousins 50% French (25% Canadian and 25% France), 25% Northern Italian, 19% Norwegian, 3% Danish, and 3% German,

As 1st cousins, we share 50% of our ancestry: 25% French-Canadian, 19% Norwegian, 3% Danish, and 3% German from my maternal grandparents who are their paternal grandparents. We have the same ethnic components but with different mixes of Italian and French. We are all Italian, French, Norwegian, Danish, and German but I’m more Italian and they’re more French. My Italian is Sicilian and theirs is northern. My French is Canadian, theirs is half Canadian and have France.

This is all based on the paper trail, as no one in either family has taken a DNA test.

There are eight of us at my generation – me and two siblings plus five maternal 1st cousins. I’m the only one who has any shade of olive skin, although two cousins have brown hair and eyes but would never be taken for Italian by skin or facial features. In fact, of the remaining six, one has red hair blue eyes, and fair skin, three have blond eyes, blue eyes, and fair skin, and one has medium hair, eyes, and skin.

I think two of my cousins resemble their French heritage and the other three resemble their Nordic heritage. One of my siblings also resembles our Nordic heritage and the other is more of a mixture with no clear heritage resemblance (though I would vote for non-Italian looks).

How would you interpret this? Does it follow the ethnic mixes?

Since you inherit 50-50 from your parents, resemblance doesn’t mean you have more of their genes, or does it when you look at inheritance from previous generations where the 50-50 rule breaks down?

Did those who resemble the Nordic just happen to get Nordic coloring, etc. in their 50% inheritance or did they inherit disproportionately from a Nordic grandparent, great-grandparent, etc?

Is it quantity or quality at play?
darkerhorse
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Re: Is It Quantity or Quality at Play?

Post by darkerhorse »

Also, can DNA testing tell what percentage of your DNA came from each of your four grandparents?
darkerhorse
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Re: Is It Quantity or Quality at Play?

Post by darkerhorse »

Knowing that the expectation of 25% each may not hold in any given case.
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MarcuccioV
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Re: Is It Quantity or Quality at Play?

Post by MarcuccioV »

darkerhorse wrote: 16 Jul 2021, 21:47 Also, can DNA testing tell what percentage of your DNA came from each of your four grandparents?
The simple answer to this question is no.

You might get an idea based on the ethnic percentages IF the ethnicities are varied enough to differentiate the individuals. For example: It would not discern what percentage came from your paternal grandfather vs grandmother since they were both Sicilian.

I have read articles where it is scientifically possible that an individual COULD get a full 50% from one grandparent and 0% from the other. It's probably not common at all, but it's possible.

You could likely tell based on looks/appearance, at least where the majority of the DNA comes from.

In the case of my 'new' cousin Debbie, she shows about 75% Northern Italian/25% Southern; whereas I show 75% Southern & 25% Northern (approximately). That's because HER dad (my mom's twin) received a higher percentage of his maternal grandparents (northern) DNA, whereas MY mom got her majority from her paternal grandparents (southern), which they then passed on to us as offspring.

It's confusing I know. There simply is no mathematical equation to justify it. It's simply random beyond the parent (50%) level...
Mark

If you ignore your foundation, your house will eventually collapse...
darkerhorse
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Re: Is It Quantity or Quality at Play?

Post by darkerhorse »

I suppose if I had a DNA test I would understand more.

"You could likely tell based on looks/appearance, at least where the majority of the DNA comes from."

I wonder how true that is? If you resemble one grandparent more than the other couldn't that just mean what you inherited from him/her is just more visible, and not necessarily more than 25%

"MY mom got her majority from her paternal grandparents (southern), which they then passed on to us as offspring."

Could you explain the math for this conclusion?
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MarcuccioV
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Re: Is It Quantity or Quality at Play?

Post by MarcuccioV »

darkerhorse wrote: 17 Jul 2021, 00:00 I suppose if I had a DNA test I would understand more.

"You could likely tell based on looks/appearance, at least where the majority of the DNA comes from."

I wonder how true that is? If you resemble one grandparent more than the other couldn't that just mean what you inherited from him/her is just more visible, and not necessarily more than 25%

"MY mom got her majority from her paternal grandparents (southern), which they then passed on to us as offspring."

Could you explain the math for this conclusion?
Just using logic (as far as the first question).

As for the math part, it's again just guesstimates. So for my mom, she most likely got an unequal distribution of grandparental DNA, roughly adding up to the percentages I noted. She may have received 75% of DNA from 2 grandparents who were of more of a southern ethnicity, but only 25% from the other 2 which were northern. The opposite for my uncle.

There are articles (many, in fact) that explain the randomness of replication much better than I can. I suggest reading several of them, as they each tend to each explain it a little differently. It's a complicated subject.
Mark

If you ignore your foundation, your house will eventually collapse...
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