Dickason/in/er/enson/Dixon DNA Project web site - Goals

The goals of the DICKASON (and other spelling variants - Dickison, Dickenson, Dickerson, Dickinson, Dickson, Dixon, etc.) y-DNA Project are:

 

1. Help researchers from common or related families work together to find their shared heritage using Y-DNA.

 

2. Identify how the participant's families are connected, both genetically using Y-DNA and through paper trails.

 

3. Identify and confirm genetic Lineages of ancestral families using both STR and SNP records.

 

When testing the Y-chromosome, there are two types of tests, short tandem repeat (STR) and single nucleotide polymorphism (SNP).  A Y-DNA test looks at male inherited Y-chromosome DNA. As the Y-chromosome is passed on from a father to his sons, it is only found in males. Y-DNA testing can then be used to trace clearly a direct paternal line.  Further information about Y-DNA STR testing is at:

http://www.familytreedna.com/faq/answers/default.aspx?faqid=8#514

 

STR tests are best for recent ancestry while SNP tests tell about more ancient ancestry. SNP testing is used to determine a person’s haplogroup which lies on the main trunk of the family tree.  Subclades are the finer branches of the trunk and SNP testing helps to find out which sub-branch of the haplogroup a person belongs to.

 

Further information about SNP testing is found here:

http://www.familytreedna.com/faq/answers/default.aspx?faqid=8#511

 

Click on the Y-DNA Results button to the right of the About This Group button for the STR page. It is in either classic or colorized format.  The SNP page will show the SNP results for our members.

 


MRCA (Most Recent Common Ancestor) or TMRCA (Time to Most Recent Ancestor)

The most important means of connecting or rejecting relationships on a scientific basis is the comparison of the y-DNA markers. The greater the number of markers compared, the less error associated with the estimate of the MRCA. The abbreviated table below shows examples for 12, 25, 37, 67, and 111 markers.

For example, a match of 23 of 25 markers only allows an estimate at 50% probability that the MRCA was not more than 11 generations ago. However, a match of 35 of 37 markers allows an estimate at 50% probability that the MCRA was not more than 6 generations ago - cutting the time in half.

You can convert the generations to years by multiplying the number of generations by an average number of years between generations. In general, you can use an average of 25 years per generation, although the average can vary from family to family. We start counting generations with the parent generation. Therefore, the father of the person tested would be 1 generation ago, the paternal grandfather 2 generations ago, etc.

These MRCA can be accessed by clicking on the link shown as TiP from the your listing of matches. If traditional genealogical records indicate that a common ancestor between you and your match could not have lived in a certain number of past generations (e.g., 4 or 5), your TiP results can be refined.

You should test more Y-chromosome DNA (Y-DNA) STR (short tandem repeat markers when you want to compare additional markers against others with similar results. Our motto could be: Test only what you need, and upgrade only when necessary.

Time to Most Recent Common Ancestor (MRCA)
Number of matching markersProbability that the MRCA was not more than this number of generations ago
50%90%95%
10 of 10 16.5 56 72
11 of 12 17 39 47
12 of 12 7 23 29
23 of 25 11 23 27
24 of 25 7 16 20
25 of 25 3 10 13
35 of 37 6 12 14
36 of 37 4 8 10
37 of 37 2 to 3 5 7
65 of 67 6 12 14
66 of 67 4 8 9
67 of 67 2 4 6
107 of 111 7 11 13
108 of 111 5 10 11
109 of 111 4 8 9
110 of 111 2 6 7
111 of 111 1 3 to 4 5

Additional STR markers will refine your matches. If you currently have many Y-DNA12, Y-DNA25, Y-DNA37, or Y-DNA67 matches you should certainly consider upgrading your Y-DNA profile to a higher level.

The level that you choose and the need to upgrade depends on:

  • Your goals
  • The amount of testing already completed by others in a group project that you are joining
  • The degree of certainty for a relationship (match) that you desire.

For genealogical matching, the most important factor is the degree of certainty that your near or exact matches are indeed related to you in recent generations. Family Tree DNA offers several levels of testing for our Y-DNA tests. The table on the right shows the time to a common ancestor for near and exact matches at different Y-DNA testing levels.

Generally, testing additional STR markers will:

  • Narrow the expected time to a common ancestor with an exact match
  • Increase the degree of certainty for a near or exact match
  • Reduce the number of irrelevant matches
You may always upgrade to a higher level of testing as your number of matches and needs change.