Archive for August 25th, 2014

August 25, 2014

Genealogy Consanguinity & DNA — #Genealogy #DNA #Kinship

by C. Michael Eliasz-Solomon

Genealogy_Consanguinity
Consanguinity Chart Now … by John J. Tierney used via CC rights

 This is a beautiful data visualization tool of “relatedness” (Consanguinity) between yourself and an ancestor/descendant. Stanczyk loves good #STEM.  Mr. Tierney modified his excellent chart to add, “What percentage of DNA do you share with your family members”.

Kinship is characterized by the sharing of a common ancestor(s).  Consanguinity is derived from its Latin root:   consanguineous ∴  “of common blood”.

Today, I wanted to use this excellent chart to talk about the three types of Genealogical DNA tests:

 mtDNA

Y-DNA

autosomal DNA

mtDNA / Y-DNA

This way a genealogist can determine for him/her-self what benefit each type of DNA testing offers. mtDNA is for tracing the matrilineal line (your mother/maternal side). Y-Chromosome is for tracing your patrilineal line (aka surname tracing) or your father’s side. These two dnas are for tracing direct descent as these sex-based chromosomes are copied identically from one generation to the next, not half/half as the autosomal dna chromosome’s dna. Correctly, said the mutations in mtDNA and Y-DNA are more infrequent than the non-sex based genome (i.e. autosome) and they are not mixed like the other 22 chromosome’s dna. If you follow the blue arrows (in the diagram) up/down your family tree that is your linear descent; so you mtDNA to trace your mother’s side and use YDNA to trace your father’s side to your proverbial mitochondrial-Eve or your Y-Adam. You are testing for the blue boxes in our diagram.

So what is autosomal DNA?

Genealogy_Consanguinity_dna1

Inside Red Lines – are autosomal DNA generations.

The autosomal DNA are the dna from the other 22 non-sex chromosomes pairs. Autosomal DNA testing is a genealogical DNA test that uses either autosomal STRs or autosomal SNPs. (STR’s are Short Tandem Repeats; SNPs are single-nucleotide polymorphisms.) However, testing companies do not currently offer autosomal STRs tests that use enough STR markers for genealogy. The preferred choice for both genealogy and ethnic population matching is microarray chips that use hundreds of thousands of autosomal SNPs.

Mathematically, speaking you need at least six generations back before you get enough certainty(99% certainty) to do matching to find distant cousins by using current Genealogical DNA testing. So if you do not have your 4x-great-grandparents’ (all 64 of them) surnames then you are NOT guaranteed to be able to use current DNA tests to determine your relatedness to another genealogist (and his/her ancestors who must also have six generations in their tree too).

I am thinking we are still one or two generations (35-70 years) away from using this as a viable technique that will work with any two random genealogists — mathematically speaking. Obvious exceptions are Icelandiks or Amish or other relatively closed-genetic populations who may have greater success (or counter-intuitively lesser) with fewer generations. Its all in the DNA and in the quality of the testing to catch the diversity in your genome.

You will notice that the fine chart we have been using, including the one with the red-lines (my lines) that indicate autosomal DNA testing candidates, does NOT show enough generations. It would need to be extended one more generation. So we need the surnames of 64 people with whom we only share 1.5675% of our DNA with. That is with direct descent. If we are matching to the autosome DNA  (i.e. our Nth cousin, M-times removed) then we are matching to someone who we may only share 0.0243% blood with. That is 2/100th of 1 percent !

Related Blog Article

<

p style=”text-align:justify;”>Violinist’s Thumb24-January-2014 – This has many great links to other articles and includes some pertinent facts on DNA to think about. A Guaranteed thought provoker of a blog.

Advertisements
Stem Cellular

Science and technology improving health outcomes

Steve Szabados Genealogy

Genealogy Columnist for the Polish American Journal and Author

From Shepherds and Shoemakers

Sharing musings, insights, resources and strategies as I discover my family history.

Find Lost Russian & Ukrainian Family

Uncovering the secrets of finding family and records in the former USSR

Historia pamięcią pisana

Historia wsi Święty Józef na Pokuciu

The Dystopian Nation of City-State

A cruel, futuristic vision created by science fiction authors James Courtney and Kaisy Wilkerson-Mills. ©2013-2016. All Rights Reserved. All writings available through Amazon.

What's Past is Prologue

Adventures in genealogy

The Family Kalamazoo

A genealogical site devoted to the history of the DeKorn and Zuidweg families of Kalamazoo and the Mulder family of Caledonia

Interesting Literature

A Library of Literary Interestingness

Globe Drifting

Global issues, travel, photography & fashion. Drifting across the globe; the world is my oyster, my oyster through a lens.

Oracle Scratchpad

Just another Oracle weblog

toledo's kuschwantz

a Polish kid and her family from Toledo

Author Michael Charton

Home of Author Michael Charton

CITY OF LIONS

A Journey through History in Search of a Vanished Family

The WordPress.com Blog

The latest news on WordPress.com and the WordPress community.

%d bloggers like this: