Monday, September 1, 2014

#FGS2014 Conference: Autosomal DNA

At the 2014 annual conference of the Federation of Genealogical Societies, Anna Swayne of presented the session “Utilizing AncestryDNA Matching to Break Through Brick Walls in your Research.” This is the first in three articles about that presentation.

Swayne gave us a brief introduction to DNA. There are different types of DNA. Y-chromosome DNA is passed down the fathers’ line (the blue line on the fan chart, below) and mitochondrial DNA is passed down the mother’s line (pink line, below). Autosomal DNA is all the other DNA passed down from all of your ancestors (green, below).

On this fan chart Y-DNA is shown in blue, mitochondrial in pink, and autosomal in green.
[Note: My diagram differs from Swayne’s in that I’ve left green off of some ancestral lines to exaggerate one of her next points: An ancestor’s DNA can drop completely out.]

Swayne showed a chart I liked so much, I’ve created one of my own (below). Seeing the chart was a light bulb moment for me. I suddenly saw how the DNA of a set of parents is slowly displaced. In my chart, blue, green, red, and orange show their DNA. Gray is DNA of others. With each successive generation, more of the original parents’ DNA disappears in this line of descent.

In each successive generation, half the DNA of the grandparents is lost.

Swayne showed another chart of alphabet blocks cleverly chosen to illustrate this. I’ve shown part of it, below. Click to see the full image on the website with both sets of grandparents, parents, and siblings.

Alphabet blocks illustration of inheritance

When you get your DNA tested from AncestryDNA, you get two types of results: an ethnicity estimate and a report of matches. (To be continued…)

1 comment:

  1. I pinned this to Genealogy-DNA. This is the coolest thing ever! I agree with your comment that it was a "lightbulb moment"! How do I politely say this...please hurry and post part two!


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