DNA and the Jordan Family

This post contains a more detailed explanation of some of the facts contained in my post on “The Jordan Family.”

The material set apart below was extracted from a paper prepared by my son Stuart Jordan.  He plans to include it in a soon to be published update of his history of the Jordan family of Halifax County, Virginia, and therefore it should be treated as copyrighted material.

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DNA Testing Overview and Family Tree DNA’s

Jordan Surname Project

Over the past two decades, Deoxyribonucleic Acid (DNA) testing has become of great value to family historians, genealogists, and those who are merely curious regarding their origins. The great thing about DNA testing is that many of our traits are passed down intact from generation to generation.

It has been more than 40 years since I participated in an undergraduate class in Genetics so I am certainly no expert in the subject, but I believe a brief overview of DNA testing is in order here.

All of us humans have 23 pairs of chromosomes which constitute our DNA and can be found in various forms in each and every cell in our body. One pair is known as our Sex chromosomes, the other 22 pairs are known as our Autosomal chromosomes. One component of each pair was contributed separately by our two biological parents (mother and father). Collectively, these 23 pairs of chromosomes determine our physical characteristics.

As their name indicates, our Sex chromosomes determines our sex at birth and are responsible for most if not all of the physical characteristics unique to our sex. There are two possible pair values for our sex chromosomes, XX (female) and XY (male). One X chromosome is always contributed by our biological mother as the only possible value, but our biological father can contribute either an X or a Y chromosome at conception, hence it is the father’s contribution that determines an individual’s sex.

The most popular of the DNA tests done for genealogical purposes is known as the Autosomal test, and is currently offered by several major firms, among them Ancestry, 23 and Me, and Family Tree DNA. The Autosomal test is great for three reasons – it tends to be the least expensive test, it appears to be the most useful for identifying other closely-related individuals on all lines (maternal and paternal) who have also been tested, and it is known for being useful in identifying the geographic origins of an individual’s biological ancestors with varying degrees of accuracy.

The other tests typically done for genealogical purposes are called the Sex chromosome tests of which there are two, the Mitochondrial (Mt)DNA test and the Y-DNA (a.k.a. yDNA) test. While these two tests are slightly more expensive, they also provide uniquely valuable information not offered by the Autosomal test. The MtDNA test is useful for determining the migratory paths of our biological mother’s female ancestral line and – for those admittedly very few societies where the family name is passed along by the biological mother – can be useful for grouping relatives by surname.

The yDNA test, which will be the subject of the remainder of this paper, is likewise useful for determining the migratory paths of our biological father’s male ancestral line and – for the majority of societies where the family name is normally passed along by the biological father – useful for grouping related males by surname. As the Y chromosome is only passed from father to son, the yDNA test can only be performed on males – females must get a biologically-close male relative on their father’s side (brother, father, paternal uncle, etc.) to take the test for them.

Very few firms offer the Sex chromosome tests for genealogical purposes anymore, Family Tree DNA (FTDNA) being one of the few. In addition to offering one of the largest databases of test takers, FTDNA also offers what are known as Surname projects where yDNA test takers can have their results automatically matched against others with the same surname (including variations). Naturally, I joined the Jordan Surname Project and took the yDNA test.

The individual genes used in the yDNA testing done by FTDNA were chosen because of their inherent stability over many generations. These are technically called Short Tandem Repeat (STR) markers, which I will not even attempt to explain here. The testing of each STR marker results in one or more unique allele values. Each group of test takers in the Jordan Surname Project appears to have a unique pattern of allele values within the first block of STR markerschosen for testing by FTDNA, known as the yDNA signature for that group. (Note: There can and will occasionally be variations in the allele values – called mutations.)

While over 680 men who have taken the yDNA test have had their results deposited in FTDNA’s Jordan Surname Project, only 25 or so have been grouped along with my results in Jordan Group #8 (JG08). All members of Jordan Group #8 linearly descend on their paternal line from a single male ancestor who took on the Jordan surname back when surnames were first being taken on, probably in the early part of the second millennia. The other groups (for example, Jordan Group #7) did not originate from the same male Jordan ancestor as did JG08.

Unfortunately, the degree of biological relationship cannot be determined by yDNA testing alone. For example, the yDNA test will not normally tell you whether two men having the same last name and similar yDNA test results are father-son, brothers, or distant cousins. Nor will it determine the degree of relationship between the identified male-line ancestors of two tested individuals. Only the documented record trail can do those things.  However, the yDNA test has already helped me identify several other Jordan men – once total strangers – who I now know are related to me and therefore confirmed their paternal-line Jordan ancestors several generations back in time are closely related to or perhaps even the same as mine – the Autosomal testing could never have done this. Furthermore, the yDNA test is a sure determinant of who is NOT related to me as a Jordan male.  If another male with the Jordan surname has yDNA test results significantly different from mine in the first 12 positions, it is for sure and for certain we did not share a paternal-line male Jordan ancestor.

Simply by submitting a saliva sample on a cotton swab, FTDNA will now perform yDNA testing resulting in no less than 37 allele values, although I found only the first 25 values to be significant for my purposes.

As of September 2020, there are over 32 unique groups in the FTDNA Jordan Surname Project, with dozens of yDNA test-taker results yet to be grouped. Some groups originated out of Ireland, some Scotland, some even Germany, but most appear to be of English/Norman origin.

Stuart M. Jordan

December 30, 2020

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Stuart’s paper continues further, but I decided to summarize the remainder of his submission as follows:

As previously stated, Stuart and my yDNA test results show us to be members of Jordan Group #8, and members of this group have a common Jordan ancestor who probably resided in southwest England in the early to mid 16th Century.  Based on Stuart’s own analysis, Jordan Group #8 may be further divided into three subgroups, A, B, and C, based on differences in the genetic STR marker known as DYS464.  In other words, over time there were slight genetic mutations that gradually differentiated members of this one extended family.  As of this time, 15 persons have been identified with Subgroup A, and they are the known and suspected descendants of Thomas Jordan of Chuckatuck, a presumed grandson of Samuel Jordan of Jamestown.  Subgroup B, consisting of 9 persons, are descendants of Robert Jordan of Caroline County or William Jordan of King & Queen County, brothers or close cousins residing in Virginia’s Middle Peninsula during the mid-18th Century. These men were related to Thomas of Chuckatuck, but the degree of relationship is unknown. Stuart and I are in Subgroup B.  As for Subgroup C, only one person has thus far been identified in that subgroup, and he resides in Berkshire, England.

Individuals are being tested in greater numbers every year.  Over time, there will doubtless be more Jordan groups, perhaps additional Jordan Group #8 subgroups, and more persons identified with each group and subgroup.

Happy testing.

Edwin Sandy Jordan   

January 2021

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