Have you seen the commercials for ancestral DNA testing where a person has thought there whole life they were one culture only to find out they are another? Perhaps a German is suddenly Scottish, or an Italian is suddenly Eastern European. Is that truly what our DNA tells us? At what percentage does our DNA override a lifetime, or even centuries, of heritage? Understanding ones past, DNA is an important tool, but it is not the only tool. Before we can use DNA to understand our past, we must first have a basic understanding of what it is and how it is used. There are three different types of DNA used in genealogy:
Y-DNA is passed along the direct male line. This makes it possible to trace a direct male descendant bake to a male ancestor on the paternal side. While Y-DNA has a very slow mutation rate, because it is only passed along the male line, every ancestor in that line must be a male to use Y-DNA. Autosomal DNA is the random pieces of DNA passed down from generation to generation. This is what most ancestral DNA tests look at. Because a person gets approximately fifty percent of their DNA from each parent, this gives an idea where the person’s ancestors originated. However, it does have its flaws if you try taking your culture from just these results. To illustrate these flaws, let’s take a look at four members of a family (identified as Mother, Son 1, Son 2, and Son 3) to see how ancestral DNA works.. While the Mother is the mother of all three sons, only Son 1 and Son 2 have the same father. All four family members were tested by the same DNA Company to insure the same testing standard. While the DNA Company has updated their result criteria, Son 2 has not updated his results and still shows the older testing categories. The Genealogical paper trail for this family indicates the Mother should be from England and Wales as well as Sweden and Norway. The father for Son 1 and Son 2 has little genealogical trail beyond himself, but is believed to have had Polish ancestry. The father for Son 3 has a genealogical trail that includes England and Wales, possible Native American, possible French, and possible African. Culturally all sons were raised under the culture of the Mother. As the following chart shows, the Autosomal DNA comparisons of the Mother to Son 3, and Son 3 to Son 1 are reasonably close for half-siblings; however, the comparison between Son 3 and Son 2 would appear to indicate little relationship. As can be seen, the Mother for this family has a high percentage of Autosomal DNA from England and Wales with the rest of her Autosomal DNA coming from Norway and Sweden. This matches her genealogy paper trail and the culture she was raised within. Son 1 and Son 3 both inherited higher England and Wales Autosomal DNA then the Mother, presumably due to the DNA of both fathers; however, Son 2 inherited no England and Wales Autosomal DNA. Alternately, Son 1 and Son 3 inherited very little Norway and Sweden Autosomal DNA while Son 2 inherited a high level of Scandinavian (Sweden and Norway) DNA. Finally, Son 2 inherited a high Europe West (France) Autosomal DNA while Son 1 inherited a very low France Autosomal DNA level. If each of these results were looked at individually, the results would appear as follows:
Understanding ones DNA is an important tool, but it is not the only tool. Because of the random nature in which we inherit Autosomal DNA, more than one individual in a family should be tested to get a full larger picture of what the Autosomal DNA truly says. Just because ones DNA says they have ancestors from Scotland that should not negate a lifetime, or even centuries, of heritage.
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Larry De Pew
Is a professional genealogist with an Associates Degree in Applied Science n Family History Research from Brigham Young University-Idaho. His areas of focus are military and great plains research. Archives
October 2023
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