Pidcock DNA Study – by Cathy Pidcock Thomashttp://www.pidcock-family.org/DNA/DNA.htmWhat is the Pidcock DNA Study?The Pidcock name is rare and one would suppose that all North American Pidcocks trace their roots to Derbyshire England where the name has been prevalent since the 16th century. Pidcocks crossed the Atlantic starting in the 17th century and the precise genealogical connections with England faded as memories and the paper trail were lost.
At the 90th Pidcock Reunion in Pennsylvania, three men gazed at the family scrapbook postcards of Bakewell and Matlock under the caption “The Pidcock family is believed to come from Derbyshire England”. One, a recent Pidcock emigrant from Derbyshire said “I’ve been reading about Genetic Genealogy and the use of DNA to unravel mysteries like Thomas Jefferson’s offspring, or the existence of a Cohain DNA signature among Jews. If the price of this test ever became reasonable for ordinary people, I’d be glad to do the test as an example of a Pidcock from Derbyshire, England”. The other two men, a Pitcock and a Pidcock, with genealogical trails back to 17th century Pennsylvania agreed, hoping that DNA would also show the relationship between their families that logic dictated but for which no hard evidence survived.
By 2004 the price for a simple 12 marker Y-chromosome test was only $99. We decided to establish the Pidcock / Pitcock DNA Project. We knew genealogy, tracing our Pidcock / Pitcock (the names were used interchangeably in England) roots and reconnecting individuals to the family tree when the paper trail was missing, was of wide interest and family benefit.
What is Genetic Genealogy?The discipline of genetic genealogy is new. It differs from medical genetics which studies specific sites, related to a disease or inherited trait, on any of the 23 pairs of human chromosomes. It differs from forensic genetics that seeks a unique genetic fingerprint, using sites on all the human chromosomes, to identify a specific individual. It differs from paternity tests that seek to assess the possibility of paternity for a son or a daughter. We are interested in a surname and in our culture that surname is passed down the male line. Genetically, a single copy of the Y-chromosome unambiguously passes from father to son with a high degree of replication reliability. A son has only 1 copy and he got it from his biological father who got it from his biological father on back through history. So, using the “junk” (medically unimportant) sections of the Y-Chromosome for surname genealogical studies is a good choice, because not only does it track with the family surname but it also has no medical or forensic use.
The goal of genealogy is to recognize families down through generations. Between individuals in the family, the goal is to recognize whether a common ancestor occurred long ago, as in the case of distant cousins, or just a few generations ago as in second or third cousins.
Researchers found recognizable locations on the Y-chromosome, called “markers” (with names like “DYS 391”). At each marker, a contiguous DNA sequence recurs as many as 8-40 times, depending on the marker. The numeric value (count) associated with each marker is the number of repetitions of its DNA sequence for an individual. The set markers and counts is an individuals Y-DNA signature – quite coarse at 12 markers and quite refined at 67 markers. At every conception of a son, the father passes on a copy of his own Y-chromosome. The replication is highly reliable, but not perfect, especially in the junk regions where an increase or decrease in marker count has no biological consequences. So a son probably has the same signature as his father, at worst off by one.
Some markers are very stable and the counts for the markers in a man today are very close to those of his ancestor 500 or a 1000 years ago. Other markers are prone to more frequent mutation, either by adding an extra repetition or by losing one, so that differences within the last 500 years can be detected. Mutations are random hiccups in the replication process that occur at conception, if at all. Once the conceived baby, grows up, he passes the mutation to all his offspring, thus producing a branch from the original Y-DNA signature. Subsequent generations pass along this mutation and may introduce other mutations at later conceptions. If we have a big enough test population, we can cluster people according to their Y-DNA signatures and deduce the sequence in which branching occurred.
Understanding that people’s research interests differ, genetic genealogy test labs offer marker tests in suites. Our lab offers suites of 12 ($99), 25 ($148), 37($189) and 67($269) markers (prices as of 2007). An analogy with zip codes helps explain the use of a Y-DNA 12, 25 or 37 marker suite. The first three digits of the zip code, identify a postal region, such as a portion of a state. Similarly the first 12 markers are very stable. They identify a “haplogroup” (a “clan” – a grouping going back to the ice age). The next 3 digits of a zip code identify the town. In much the same way, near matches in the 25 marker suite (original 12 + 13 more markers, some of which are more volatile) identify a family. Finally the zip + 4 identifies the actual house. Extending to 37 markers distinguishes amongst branches within a family.
If two men differ by more than 1 or 2 counts in the first 12 markers, their common ancestor occurred long before surnames were chosen and there is no way they can be related in the genealogical time frame.
Men who match within 3 marker counts in the 25 marker set are probably related, though the common ancestor may have lived several hundred years ago.
Extending the study to 37 markers allows identification of branching amongst lines that match on all 25 markers and yet know of no common ancestor. There is a 67 marker test providing further differentiation. Only 1 person in our study has used it. He was seeking all the information he could find on his biological father.
Beyond price and identifying the genetic test that best served our genealogical quest, we needed to address issues of safety and privacy because we are using personal material. The test is a simple, painless, non-invasive cheek swab. The test kit contains two vials with preserving fluid. One collects the cells that have sloughed off from the inside of each cheek during the night with a little plastic rake first thing in the morning.
We chose Family Tree DNA, a company run by scientists with a focus on genetic genealogy. When an order is placed, a numbered kit is mailed to the client. All paperwork connecting client to kit number is stored at one location. The client maintains control of what is done with the sample and whether the results are shared with anyone. The lab receives, tests and stores the samples, identified only by “kit #”. Unless instructed otherwise, the sample is stored for 25 years, so the client can order further tests without recollecting sample. Each suite of tests contains some control markers that are retested to be sure the retest results are in-synch with the original results.
Family Tree DNA test results have been validated by agreement with results from other labs for the same person’s DNA. Further confirmation occurred when the DNA of a client, who knew his ancestor chose a non-Pidcock name, matched other Pidcocks.
We are quite fortunate that National Geographic has mounted a 5-year study in conjunction with IBM and Family Tree DNA to test people all over the world for haplogroup (“clan”) and a basic set of 12 very stable markers to understand these migration routes. This means that Family Tree DNA, with 110,908 Y-chromosome DNA records (as of 2007) has a lot of experience in the characterization and rates of mutation of different markers. When one uses this lab, one learns one’s haplogroup automatically. They have developed a prediction tool that compares Y-DNA signatures to predict a probability of time back to most recent common ancestor. They make it easy for the client, if he chooses, to upload results into a public data base where they can be compared with those of people testing at other labs. Finally, when a new set of markers is offered for analysis, they are chosen based on usefulness in genealogical work.
What have we learned about Pidcock/Pitcocks? Our first discovery was that some American Pitcocks closely match the DNA signature of our Derbyshire emigrant. We later found American Pidcocks who also matched. One current quest is to understand how the branches represented, evolved. Some of the men in this category, have no idea how they are related to other Pidcocks or Pitcocks. The hope is that by finding others with similar DNA we will be able to form a tree, based on the physical evidence of who is most closely related to whom. Folks on the same branch can share genealogical information.
Our next discovery was a surprise. The original American Pidcock and Pitcock in the study were unrelated even though both had well documented paper trails back to early 17th century Pennsylvania. Through testing descendents of 3 of the 4 sons of Jonathan Pidcock, who relocated from Bucks Co. PA to Lambertville NJ in the 18th century, we see the descendants are clearly related. Furthermore, with so many well documented generations we can see that the Y chromosome replication mechanism is a little more error prone, resulting in a higher mutation rate, in the Bucks Co, PA Pidcock line than the Derbyshire Pitcock-Pidcock line.
About this time a descendant of William Hazelgrove Pidcock, the 19th century Mormon missionary, joined the group. To his initial dismay, his DNA was much different than the first two Pidcock/Pitcock families we had studied. They were both descended from Anglo-Saxons who probably came from Denmark (haplogroups “I1c” for the Derbyshire group and “I1a” for the Bucks Co. PA group). His was “R1b1” indicating Celtic or southern European roots. Since then men descended from 3 of William Hazelgrove Pidcock’s wives have tested and all have the same DNA signature. This family is now eagerly seeking other Pidcocks especially those with Nottinghamshire roots in hopes of establishing a trans-Atlantic link.
To date we have 1 each of 3 other DNA signatures.
One of these is another English Pidcock. There are several Pidcock lines in Derbyshire, with long genealogies who have been unable to confirm a common ancestor through regular genealogical research. DNA analysis offers another route to recognize biological connection. In this case it shows that tracing one’s roots to Derbyshire, is insufficient proof of family connection (the same situation as we found with early Pennsylvania Pidcocks/Pitcocks). More genetic data on Pidcock/Pitcock lines with genealogical records going back to Nottinghamshire and Derbyshire will help identify and characterize family units within the our surname.
We have one Pidcoe in the study. Pidcoes believe an early 18th century Pidcock migrating to western Pennsylvania and where the family changed its name. The difficulty is that there are very few male Pidcoes – the only other one we have found, ordered the test kit but did not return it and has not been heard from since. He may have died.
The last Pidcock with no match as yet, is trying to learn anything about his Pidcock roots. In all three of these cases, being the only one with a different DNA signature, one wonders about undocumented paternity (adoption, infidelity). When one finds another Pidcock/Pitcock with the same signature, it stops being a personal issue and becomes a shared research project to understand the family history and evolution.
The more people we have in the study, the better we can characterize the Y-DNA signature and replication rate of each Pidcock/Pitcock family. We can even work backward to postulate the original DNA signature when surnames were selected. With this information, we can help modern day Pidcocks and Pitcocks who would like to reclaim their roots but have no starting place but their own DNA. Along the way, our family has already been asked to aid in a search for identity. One man, whose DNA is similar to the Bucks Co. PA Pidcock line, joined our project while searching for his biological father. He has since learned a name and location for his father and when he finds him, we may find another Pidcock “cousin” and learn another story.
This is fascinating and safe study – our personal mystery. I hope other Pitcocks and Pidcocks will be inspired to join it.
http://www.pidcock-family.org/DNA/DNA.htm
