NEW CALVERT GENEALOGY WEBSITE:
Understanding Your DNA Sample and results:
Most of us are Lay-persons to the study of DNA and the results of DNA sampling. Moreover, how the results are compared, analyzed and interpreted are important to understanding how to use the results in order to research family history.
Among participants whose results have been obtained, the Objective is to determine the degree of relatedness when considering DNA test results that are not exact matches.
Surnames begin and end the establishment of the relationship among different families. When an exact match occurs on a 12 Marker Y DNA test, you have an excellent tool to determine those whom are and are "not" related within a group of people that share the same or similar surname.
When 12 Marker Y DNA test results indicate that two people are related, it is important to consider the time frame of the oldest known or MRCA ancestor of the DNA sample participant and in doing so, establish a logical approach to using the scientific data for the two participants being compared...this oldest common ancestor or rather, the "Most Recent Common Ancestor" or MRCA is the key to continued Research.
In order to establish a time frame to the MRCA is shown as a range of time, with probabilities. Y-DNA testing does not identify the common ancestor, or specify an exact time frame. Instead, the time frame is a range of generations, with a probability of whether the common ancestor occurred within the range.
A 12 marker 12x12 Match:
The range of generations for when the common ancestor occurred, is 1 to 62+ generations at a 95% confidence level. An exact end to the range can not be scientifically identified. Having a common surname establishes the end of the range as the time the surname was adopted.
Using a figure of 25 years per generation, the range for the time frame of the MRCA is 25 to 1550 years. Having a common surname reduces that range. Surnames evolved at different times in different countries. If, for example, surnames evolved in your ancestral country in the 1400's, then the range for the time frame of the MRCA would be 25 to 600 years.
The next step to interpreting your results is to look at the probabilities associated with the time frame of the MRCA. Scientists calculated these probabilities, and divided the range of generations into 3 parts, or subsets. These 3 subsets are the generations to the MRCA at a 50% probability, a 90% probability, and a 95% probability. For those who are not familiar with probability, a 50% probability means that half the time the common ancestor would occur before the number of generations specified, and half the time the common ancestor would occur after the number of generations specified. For the 90 and 95% columns in the chart below, these columns mean that 90, or 95%, of the time, the common ancestor occurred within the specified generations.
For a 12/12 match, the chart below shows the number of generations for the common ancestor, and the probability:
Probability: 50 90 95
Generations: 14.5 48 62
As shown in the chart above, a 12/12 match indicates that 90% of the time, the common ancestor occurred within 48 generations.
95% of the time, the common ancestor occurred within 62 generations which, using 25 years per generation is 1550 Years.
It is a general assumption that most surnames were recent... In terms of Calvert the earliest documented use of the surname is approximately 1400. Therefore the surname fits the known historical context of written history and 600 years is very common for Western Europe and English Origins.
It is fair to make the assumption that an MRCA occurred within the period of 600 years for the surname Calvert or a derivative of that Surname.
Scientifically, the two partipants with matching DNA at the 12 Marker test level have a common ancestor with the same surname or Variant within the past 600 years.
If the common ancestor has been identified by family history research, and there is an adequate paper trail, these probabilities aren't significant. The common ancestor has been identified, and the purpose of the Y DNA testing is to confirm the research.
When a common ancestor for participants is not known, the scientific data and probabilities in comparing DNA results become extremely important.
The following comparison demonstrates why this is so and why a 25 Marker Test becomes more granular and of great importance.
Probability 50 90 95
Generations 7 23 30.4
With a 25 Marker DNA test, the time frame is considerably shorter than with a match on the 12 Marker test, hence more granular and more certain. Since the time frame is shorter, roughly halved, we have moved our consideration of an MRCA from 600 to 300 years.
Documentation and a word of Caution:
It is important to consider the documentation of participants which are considered proof of ancestry to a certain point in family lineage.
Use accepted Genealogical practices for proof of evidence of family lineage. Primary documentation itself may be factual, legal and without question, dependable. But even the application of proof via a paper trail can be based upon conjecture. Exact data infers exactly that: Exact data. How it is used to prove that the person to which the data applies is often misused, abused or accidentally misleading.
It is not the purpose of this project to assume any responsibility for documenting, verifying or validating sources of documentation or how such are applied to the history of an individual who is the focus of the study. The administrators today and will in the future request specificity and honesty in providing information on family descent.
For users of the data supplied jointly to this website, keep this caution in mind.
The 12 marker test may be sufficient in some cases but the current hosts(Administators or facilitators of the Calvert DNA study highly recommend that the 25 Marker Test be used as the base for scientific data sampling.
We also highly recommend that those involved with the DNA sampling and research publish the known ancestors and related material for future use by other family researches. Make the data available for use, not just the DNA results.
The Surname Projects in which an MRCA is not identified, we highly recommend continued pursuit and an upgrade to the 25 marker test.
When the existing results belong to Haplogroup R1b, it is almost essential to use the 25 Markers measurement.
An upgrade to 25 Markers will reduce the time frame for the common ancestor. In addition, an upgrade to 25 Markers for a 12/12 match may also show that the participants are not related in a genealogical time period. A 12/12 match could become, for example, a 19/25 match. On the otherhand, there are many markers which are significantly and statistically hiper, or volatile and where a -2 match on a 12 marker sample shows an unlikelihood of ancestral nearness, a -2 or -3 on a 25 marker sample is the opposite.
The chart below shows the probabilities and generations for the 25 Marker Test.
Probability in numbers of generations -- 50% 90% 95%
12/12 Match 14.5 48.0 62.0
11/12 Match 36.5 84.7 103.4
25/25 Match 7.0 23.0 30.4
24/25 Match 8.0 41.0 52.0