The Math

[darkerhorse]

I just want to clarify the math.

If my father was 100% Sicilian and my mother was a combination of French, Norwegian, Danish, and German then all my siblings and I will have the same 50% percent Sicilian in our DNA but could vary in our ethnic percentages from our maternal side.

So, none of us can be more Sicilian than the others, but one of us can be more French etc. than the others?

Is that the case? If so, is there any other way to differentiate paternal heritage among siblings? I assume all males would share the same Y DNA as the father.

You can substitute Italian for Sicilian if you want in this example. The important point is that it assumes my father is a thoroughbred Sicilian/Italian and my mother has no Italian ancestry.

[MarcuccioV]

I just want to clarify the math.

If my father was 100% Sicilian and my mother was a combination of French, Norwegian, Danish, and German then all my siblings and I will have the same 50% percent Sicilian in our DNA but could vary in our ethnic percentages from our maternal side.

So, none of us can be more Sicilian than the others, but one of us can be more French etc. than the others?

Is that the case? If so, is there any other way to differentiate paternal heritage among siblings? I assume all males would share the same Y DNA as the father.

You can substitute Italian for Sicilian if you want in this example. The important point is that it assumes my father is a thoroughbred Sicilian/Italian and my mother has no Italian ancestry.

Yes, you are correct. 50% DNA from each parent, no more, no less. So, in your hypothetical situation, assuming your dad being 100% of a single ethnicity (Sicilian in your case), then you and your siblings would carry 50% of that ethnicity.

Since your mother has a mix of at least 4 ethnicities, you (and your siblings) would carry 50% of that mix. You are also correct that it will vary between siblings, even to the extent that one may carry 0% of one (or more) of the 4 (in an extreme example).

The only way to verify would be to each take a DNA test and compare results. Bear in mind the science isn't exact. Don't expect a test to come back as "exactly" 50% Sicilian, for example (Especially since Sicily is quite the ethnic melting pot). But as to your basic hypothetical math question you are correct...

[darkerhorse]

Thanks for confirming my grade of A+ on math. Of course, I'd allow for margin of error + or - 50%.

I was just summarizing what I understand others (including) you had written in this forum.

Unfortunately, I'm not so interested in my mix from the maternal side. Unless there was a surprise. There is family lore of American Indian ancestry in the French-Canadian line but who with French-Canadian ancestry doesn't have that story?

Back to my example.

So, Italian DNA is just more visible in the sibling with dark hair, brown eyes, and olive skin than in the sibling with red hair, blue eyes, and fair skin and freckles. The Italian DNA of the "Norwegian" sibling is hiding.

[MarcuccioV]

So, Italian DNA is just more visible in the sibling with dark hair, brown eyes, and olive skin than in the sibling with red hair, blue eyes, and fair skin and freckles. The Italian DNA of the "Norwegian" sibling is hiding.

Correct. How looks coordinate with DNA percentages is far beyond my pay grade, but it works out how it works out...

[darkerhorse]

The red-head actually had hair texture more like some on the Sicilian side- tight waves - not quite kinky or 'fro.

The whole question of "he/she takes after him/her" would be fascinating to answer with genetics.

We usually mean things visible like physical appearance, temperment, talents, etc. but you wonder about the mechanics and what inheritance lies beneath the surface.

[darkerhorse]

I think most people wouldn't be surprised to learn that Moses and Samuel were brothers, but many would be surprised to learn that Jerome also was a brother.

[MarcuccioV]

I think most people wouldn't be surprised to learn that Moses and Samuel were brothers, but many would be surprised to learn that Jerome also was a brother.

In my family, the interesting scenario was my mother & her fraternal twin brother -- although they both had aspects of both my grandparents, they were almost diametrically opposed -- in almost every aspect (looks, personality, etc).

The only thing they shared was an impressive talent for cooking (which was odd as my grandfather didn't cook and my grandmother's cooking left much to be desired -- in my opinion, anyway)...

[darkerhorse]

So, ironically they'd never even be taken for siblings by strangers.

[MarcuccioV]

So, ironically they'd never even be taken for siblings by strangers.

No, not at all. In fact, I recall people that did not know them being in disbelief that they were even related, much less twins.

Whereas my wife and her late (younger) sister, although different enough, were always guessed as sisters (and sometimes mixed up by people who did not know them well)...

[darkerhorse]

In some cases with siblings who don't resemble each other, each sibling looks like one parent, and you'd never guess that he/she belonged to the other parent too.

[MarcuccioV]

In some cases with siblings who don't resemble each other, each sibling looks like one parent, and you'd never guess that he/she belonged to the other parent too.

Yes, I've seen that many times. With my mom & uncle, each resembled one parent more (my mom like my grandfather, my uncle my grandmother) but each had physical attributes of both.

What was unusual, despite being children of the same pregnancy, there was no blending of those attributes between them...

[darkerhorse]

There are some interesting studies linking the evolution of physical attributes like skin, hair, and eyes to diet, UV rays and geographic location.