Q. What is a SNP and how can I use them to figure out how I'm related to my matches?

A. SNP is short for single nucleotide polymorphism. They are the most common type of genetic variation among people. Each SNP represents a difference in a single DNA building block, called a nucleotide. For example, a SNP may replace the nucleotide cytosine (C) with the nucleotide thymine (T) in a certain stretch of DNA. When this occurs it is a mutation (or change in your genetic code) that we can then use to determine how people are related to each other. Since these mutations occur in individuals, that means that people who share the same SNP ultimately inherited them from the same individual—a common ancestor.

A SNP occurs approximately every 120-140 years.   From Big Y testing we know that Sam Vass, Robert Billstein and a Peruvian share a common SNP called the R1b-FGC20980 that occurred around the 10th Century.  As you can see from the tree on the results page,  VASS and BILLSTEIN also share another SNP that occurred later called the FGC21046.  Since SNPS occur every 120-150 years (on average), both men have additional private SNPs that SO FAR no one else shares.  Some of these private SNPs can be revealed, placed and dated by their matches in this group.  As these private SNPs become known SNPs, new branches will be revealed.  So by testing SNPS you can not only add your own branch to our DNA/phylogenic tree, but you will help the entire group.

Q. Why do all of my matches show different terminal SNPs.  Are we different?  

A. Many of your matches have exactly the same KNOWN SNPs.  You will only start to have different terminal SNPs after you have tested for some of the new private SNPs by doing a SNP Panel, Big Y or even an individual SNP test.  

Q. Should I upgrade to 67 or 111 markers, or buy a SNP Pack?

A. The answer to this is different for each cluster.  Generally it is best to do Big Y or buy a SNP pack.  However, if a super close match has already done Big Y, you may not be the best person to do this test.  However, you still might be a good candidate to either test all of the private SNPs of someone who has done Big Y or to do a SNP Panel.  Ask me if you're interested in additional testing.

Q. What is Big Y and how can it benefit me?

A. Big Y is a direct paternal lineage test that looks at 12 million locations on the Y Chromosome. Big Y is able to detect new branch markers that are unique to your paternal lineage, surname, or even you. Because a SNP will mutate approximately every 144 years (one of the nucleotides A,C,G or T will change), the age of a SNP can be calculated, and the more men who do Big Y, the more accurate this date becomes.

In this group we have VASS & BILLSTEIN have done Big Y and have tested positive for both  R1b-FGC20980 and FGC21046.  (See YFull results).  So our DNA tree is only starting to develop branches.  With each new Big Y we will expand branches and discover more SNPs.  This group is still in need of more Big Y, but some men are better candidates than others. For example if one of your very closest STR matches has already done Big Y your contribution will be less than if you have no close matches who have done Big Y. When you have a super close match who has done Big Y there are some very inexpensive ways to attach your ancestor to the SNP tree without doing Big Y.

YFull assumes that a new mutation/SNP occurs around every 144 years.  So using this rate we would expect to see 7-8 SNPs each occurring between  900 CE -1950 (birth of individual).  So based on 7 SNPS we perhaps could see a new SNP appear as follows:  1044 CE, 1188 CE, 1332 CE, 1476 CE, 1620 CE, 1764 CE and finally ca 1908 CE.  

So the more men who do Big Y, the more new SNPs will be revealed that occurred AFTER 900 CE. When two or more men share a SNP, that SNP becomes a common SNP and its position on the SNP tree can be determined and a date can be predicted. But as you can see that leaves scores of SNPs that have been found in some of your matches. If you also do Big Y you will be able to pull out even more of these SNPs, get them dated and contribute even more of your own novel SNPs.

Q. I've already taken a Y-Chromosome test through Family Tree DNA. Why should I take more tests?

A.  Most of you have taken one of the basic Y-DNA tests which only test Short Tandem Repeats (STR). STRs are different than SNPs in that they represent a certain section of DNA that tends to repeat itself often. These tests are very useful to determine relatively close relationships, but they aren't good for establishing the tree shown above because they tend to mutate back and forth, and are therefore less precise.

In many cases, an STR test is the best test to take. Not only does it allow you to find close genetic matches, it can also be used to predict your SNP by comparing your STR results to others who have also taken SNP tests. If it wasn't for your STR test, you would not have been identified as a member of this cluster! However, STR tests can only go so far and for the type of research we are looking to do in this project, SNP tests are also necessary. Projects like this one are useful to help you decide which "upgrade" tests are necessary and which are not.