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To reference the discussion below, it would be helpful to open the Y-Results page of this web site in a new tab.

In this discussion when I refer to an outcome for one of the 37 marker sites tested in our project, I am referring to the number of repeats of short DNA segments that were detected at that site. The marker sites tested in our study are termed STRs =Short Tandem Repeats.    As an example, it can be seen in the y-Results page that for the first marker site (#393) all nine Deweeses have 14 copies of the short DNA segment at this site. Whereas R. L. Dewease, who carries a Wilson Y chromosome, has 13 copies at this site.  See below for Technical details of site #393 on the human Y chromosome.

The outcomes for each of the 37 marker sites are shown for the ten participants (nine Deweeses and one Wilson)  in the y-Results page. I have colored coded the outcomes at marker sites for which there were differences among the  Dewees(e) participants. There were eight such marker sites where differences occurred.  Mutational differences at DYS389i and DYS389ii are in the same STR site, therefore these represent one site in the total count of eight sites.

Marker sites in the top row colored red are those known to have high mutation rates. In fact, six of the 11 marker sites for which there were differences among the  Dewees(e) participants are in this high mutation category. Mutations in these markers produce differences among surname lineages in a genealogical time frame and help explain the Dewees(e) data.

Deduced Ancestral Haplotype (DAH) based on outcomes from Y STR markers

Before discussing results of the Dewees Surname Project, I will offer an explanation of how to estimate the Y chromosome marker site values for the Project’s common male ancestor, in this case Garrett Hendricks de Wees. For STR marker sites on the Y chromosome, an individual’s haplotype is the set of outcomes for the several marker sites tested. Due to chance mutations along the Y chromosome, the haplotypes of descendants of a common ancestor will change over time, deviating from the ancestor’s haplotype. Given the haplotypes of a number of male descendants from a common male ancestor, it is sometimes possible to deduce the haplotype of this distant common ancestor. This is termed the Deduced Ancestral Haplotype (DAH) and is shown in the Y-Results table in blue.  The DAH is determined through the use of genealogical records and the mutational events required to work back to the common ancestor’s haplotype. This information is useful in interpreting the results of surname projects that utilize STR markers on the Y chromosome, such as this project.

Analysis of the Dewees(e) Surname Project Results

The Dewees(e) Surname Project assumes that WILLIAM, CORNELIUS, and LEWIS (LAMBERT)  are sons of Garrett H. de Wees. Historical records prove this relationship for William and Cornelius, and strong circumstantial evidence exists for Lewis as the son of Garrett as well. The possibility that Lewis is the son of Garrett is addressed below. The Y STR data discussed below supports this assumption but can not prove it. In addition, it is assumed that true Dewees(e) paternity exists for all nine Dewees(e) participating in this surname project.

Genealogical records indicate that CD and brothers, AAD and JBD, are fourth cousins once removed who trace their ancestry seven and eight generations, respectively, back to WILLIAM.  (See participants' lineages in PATRIARCH section.)

MFD and JTD are fifth cousins who trace their ancestry eight generations back to LEWIS.

ACD, HWD and RBD are sixth cousins who are descendants of CORNELIUS, eight generations back.   Also, ACD and HLD are fifth cousins.

The three lineages shown below, therefore, are assumed to be independent lineages descended from the same common ancestor, Garrett H. de Wees, through his three sons.  

Genealogical pedigrees for nine project participants can be seen at the Patriarchs page on this web site.

As shown on the y-Results page, of 37 marker sites tested by FT DNA in the Dewees(e) Surname Project, variation among participants occurred at eight sites shown in the green shaded areas.  The values for these eight marker sites are presented in the table below for each participant.   The string of numbers for each participant is his haplotype.  The participants are arranged into their lineages from the three sons of Garrett H. de Wees.

As is expected for brothers, AAD and JBD share identical haplotypes which they inherited from their father.

Marker sites:  389i/ii    458      464a     460       576         570       CDYa        CDYb

C. D.               14/32      15        11         11          17             19         35              41
J. B. D.            14/32     16        11         11           16            19         35              41
A. A. D.           14/32     16        11         11           16            19         35              41       

M. F. D.            14/32     15        11         10           16           20          34              42
J. T. D.              14/32     15        12         10           16           20          34              40
D. D.                 14/32     15        11         11           16           20          34              42

R. B. D.              13/31    15        11         11            16           20         34              43
A. C. D.             14/32     15        11         10            16           20         33              42
H. W. D.            14/32     15        11         11            16           20         34              41
H. L. D.              14/32     15        11         11            16           20         34              43
L. H. M.             14/32     15        11         11            16           21         34              42 

DAH                  14/32*   15*      11*       11*          16*          20*       34*            **

* Among these seven marker sites, two of three lineages produced nearly the same outcome which is most likely that of their common ancestor, Garrett.

**Ancestral value cannot be determined for CDYb, which is reported to have a very high mutation rate:  (John F. Chandler Journal of Genetic Genealogy 2:27-33, 2006)


The following conclusions are based on the possibility of chance mutations among 37 tested marker sites occurring during the eight to nine generations that separate the nine Dewees(e) project participants from their purported common ancestor, Garrett H. de Wees. Variations were detected in only eight marker sites. Due to this small amount of variation and the small sample of Dewees(e) participants, the following conclusions are subject to the effects of chance sampling. With the use of more marker sites and additional participants, conclusions could vary somewhat from those presented below.

1. In WILLIAM’S lineage, CD and AAD/JBD differ in two of 37 tested marker sites, #458 and #576.
This level of similarity in Y chromosome makeup is within the range predicted by genetic theory for fourth cousins. Based on theoretical considerations published by Bruce Walsh, the Time back to a Most Recent Common Ancestor (TMRCA) between two relatives, given a difference of 2 out of 37 tested marker sites, can be estimated for specified mutation rates. Use of the TMRCA Calculator at permits the following probability statement to be made for the estimated TMRCA: “there is a 47% chance that the two individuals (such as CD and AAD/JBD) shared a common paternal ancestor within the last 9 generations”. This calculation of “cumulative probability” assumes an average mutation rate of 0.004 for the 37 marker sites. The TMRCA Calculator also reports “…the two individuals most likely shared a common paternal ancestor 7 generations ago”. The actual number of generations back to their common ancestor for CD was five and for brothers AAD and JBD it was six. These observed numbers of generations of five and six compare closely with the theoretical prediction of 7 generations.

2.  As is the case for WILLIAM’S descendants in (1.) above, two descendants of  the LEWIS lineage , MFD and JTD, also differ in only two of the 37 DNA marker sites.  Therefore, the calculations used above also apply to MFD and JTD such that two such individuals  likely shared a common ancestor 7 generations ago.  Being fifth cousins, MFD and JTD shared a common ancestor six generations back, which agrees closely with the theoretical prediction of 7 generations.  DD and MFD differ at only one site out of 37.  The FTDNA TiP calculator computes that there is an 89% chance that two such individuals share a common male ancestor within the last 8 generations. DD and MFD, in fact, share their common ancestor, Lewis, eight generations back.  See their lineages in the Patriarchs page.

3. In CORNELIUS’S lineage, ACD, HWD and RBD are sixth cousins who differ in three or four of 37 tested marker sites, 389, 450, CDYa, and CDYb.   Given this level of difference and use of the TMRCA Calculator as above, “there is a 50% chance that two such individuals shared a common paternal ancestor within the last 13 generations”. And, from the TMRCA Calculator,”… the two individuals most likely shared a common paternal ancestor 11 generations ago”. These theoretical values calculated for TMRCA are based on an average mutation rate of 0.004 and are, therefore, over estimates because of the reported high mutation rates of the CDY DNA marker sites. In light of this, the observed differences (at three marker sites) between these sixth cousins agrees with the theoretical prediction within the limits of chance sampling.    
    Fifth cousins ACD and HLD differ at three sites, two of which are in the highly mutable site CDY.  The Tip calculator at  reports that there is a 72% probabilty that two such individuals share a common paternal ancestor within the past 12 generations.

      An interesting note for these four relatively closely related Deweeses; ACD spells his surname Dewees and HWD, HLD  and RBD spell theirs DeWeese. As more of Cornelius’s descendants join this surname project, it may be possible to assign unique, deduced haplotypes to these Dewees and DeWeese sub-lineages.

4. In Dewees genealogy, the question of Lewis (Lambert) Dewees’s place in the Dewees family has been an issue. Was he a brother to William and Cornelius as suggested but not proved by genealogical records? To help answer this question, the haplotypes represented in the three Dewees lineages in the above table (WILLIAM, LEWIS, and CORNELIUS)  can be compared to the deduced ancestral haplotype (DAH) of their common ancestor, Garrett H de Wees. If the haplotypes of Lewis’ descendants are similar to the DAH,  then this would argue that Lewis could be Garrett’s son.  Because of the very high mutation rate of CDYb, as referenced above and its ambiguous results in this data set, I have removed it from this discussion. 
    Among descendants of Lewis, DD exactly matches the DAH,  MFD differs at one marker site and JTD differs at two sites.  In Cornelius's line, HWD and HLD exactly match the DAH.  RBD differs from the DAH at one marker site, and ACD differs at two marker sites. Whereas descendants of William, CD and AAD/JBD, differ from the DAH by four marker sites.  This information places Lewis’ descendants as close or closer to the DAH (Garrett H. deWees) as the descendants of the two verified sons of Garrett H. deWees, Cornelius and William, thus supporting Lewis as son of Garrett. 
   The above Y-DNA test comparisons can not prove Lewis to be a son of Garrett H. de Wees, however they do provide support for this possibility. The data also would support Lewis as a nephew or other close male relative of Garrett Hendricks deWees.
    For a thorough review of the historic records suggesting that Lewis is the son of Garrett Hendricks deWees, see the article by Dr. Jack C. Vaughn and Ted D. DeWeese at:

5.  Two participants in this project represent possible occurrences of non-paternal events somewhere in their lineages.   Their Y-DNA patterns do not match the patterns of other men having their surnames.

   A.  The Y DNA pattern of Mr. DeWease, listed in the results table as ungrouped, differs greatly from the typical Dewees(e) pattern.  His Y-DNA pattern, in fact, is a perfect match to three men in the FTDNA database all having the Wilson surname.   Mr. DeWease reports that his genealogical records indicate that he likely is a descendant of Peter Wilson. 

  B.  Mr. Miles is shown in the results table as a descendant of Cornelius Dewees. Mr. Miles was identified as having a Dewees(e) Y-DNA pattern following a search in the FTDNA database for Y-DNA matches to the Dewees(e) pattern. Originally, Mr. Miles was a participant in the Miles surname Project, but his Y-DNA pattern differed greatly from patterns of other Miles men. He was initially placed in the Cornelius group of this project because his Y-DNA pattern differs at only two marker sites (DYS570 and CDYb) from the Modal pattern for this subgroup. However, with the addition of participant #340505, Mr. Miles also differs at two sites from the modal pattern in the Lewis group. Because Mr. Miles differs at four sites from the Modal pattern in the William group, he likely is not a descendant of William. Due to the small number of mutational events in these data, we are unable to say with certainty from which of the three sons Mr. Miles descends, but most likely it is Cornelius or Lewis. This Miles family has joined our project and is currently reviewing historical records for a possible intersection of the Miles and Dewees(e) families.

6. Dewees family historians report that virtually all U. S. Dewees(e) families studied in detail can be traced back to the Garrett Hendricks deWees family who immigrated from The Netherlands to New Amsterdam (now NYC) in approximately 1663.   As more Deweeses join the Dewees Surname Project, thus providing additional Y STR data sets, it may soon be possible to assign a Dewees(e) male to his correct lineage and sub-lineage based solely on his Y chromosome makeup.

7. The Dewees(e) Haplogroup (Hg)
As shown in the Y-DNA Results page, three Dewees(e) males are confirmed by SNP (Single Nucleotide Polymorphism*) testing to belong to the I-M223 haplogroup, and #181226 (AAD) belongs to I-Z190 haplogroup. Their haplogroup designation is colored green. The haplogroup designations for the remaining Deweeses are in red and “have been predicted by Family Tree DNA based on unambiguous results”, primarily from their STR patterns (haplotypes). The I-M223 haplogroup identifies a group of people all of whom share the M223 SNP, a rare mutation that occurred in their common male ancestor several thousand years ago. Males having a Y chromosome with this mutation were present in northern Europe after the last ice age and today are concentrated in the countries of Denmark, Germany and the Netherlands. This is in agreement with the origins of the Dewees(e) family in that family historians report the family founder Garrett Hendricks deWee immigrated from the Netherlands to New Amsterdam (now NYC) in about 1663. Information about this haplogroup can be seen at
The project administrator (kit# 181226, AAD) has tested several additional SNPs and is shown as belonging to haplogroup I-Z190. This is a subgroup of the I-M223 haplogroup whose members have tested positive for a more recently occurring SNP, Z190. It is very likely that all Deweeses are in the I-Z190 subgroup as well.

* SNP- Mutations at the single nucleotide level, for example T changed to C, are rare, occurring at a rate of 1/million. Once a SNP mutation occurs on the Y chromosome it persists in all male descendants in the resulting lineage. This group of men, all carrying the same unique SNP on their Y chromosome, represent a subgroup of the human population known as a Y haplogroup.

Andrew A. Dewees
Administrator, Dewees(e) Surname Project
Revised May 30, 2013/ July 18, 2014/August 22, 2014


Technical details of site #393 on the human Y chromosome:

As noted above, site #393 on the Y chromosome (DYS393) of Dewees males in this project contains 14 copies of a short repeating DNA segment. Through the use of nucleotide sequencing techniques, geneticists have determined that the short repeating sequence at this site is AGAT ( Therefore, under the nucleotide pairing rule (A-T and G-C), the double stranded DNA at this location in these Dewees(e) males appears as follows:

                                 1      2      3       4      5       6       7     8       9      10   11     12   13    14

On either end of this repeating sequence are nucleotide sequences (xxxxxx…..xxxxx) unique to the DYS393 region that are used to identify and amplify this entire sequence from a cheek cell DNA sample. The resulting pool of amplified DNA molecules from this site is then separated from other DNA molecules and sized to determine the number of repeat copies present at this STR site.

Among males sampled world-wide, the number of AGAT repeats at DYS393 is reported to vary from 9 to 17. This degree of variability is not unusual for STR DNA marker sites and is the basis for their use in characterizing surname lineages in genealogy studies. The variation found in surname lineages for STR markers such as DYS393 is most likely due to occasional errors in DNA replication, which usually increase or decrease the copy number by one. As evidence of this, all eight mutations in this study resulted in the increase or decrease of one repeat unit from the modal number of copies (see y-Results page).

Andrew A Dewees
9-21-2010/ 5-30-2013/7-18-2014/8-22-2014


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