How Many Markers?

The question comes up as to whether it's better to get the 12 marker kit or the 25 marker kit or 37 marker kit or the 59 marker kit.  There are some reasons for choosing 12 or 25 initially. The 25 marker test is going to provide a shorter TMRCA (Time To Most Recent Common Ancestry); in other words your probabilities of matching another will occur within a shorter number of generations. (That is, you will know that there's a 50 percent chance you match someone within 8 generations as opposed to 14, for example). One reason  is, from a practical standpoint, the cost of the test, others are considering what results one would like to get. Remember also that genealogy DNA testing is not an exact science, but another good way, along with a documented paper trail of baseline ancestors, to sort out surnames. The 37 marker test discussion is here

After the cost is considered, the next considerations, I believe, are these.

So, let's use some examples:

Therefore, going to recommend this. Starting with the 12 marker test will save money for the group as a whole, and will, I think, encourage more participants in the program to test against. If you want to, initially get the 25 marker test, but if there are no other 25 marker participants, you will not have a base to test against. . If you get the 12 marker test, consider that you may want to upgrade to the 25 markers if you have a 12/12 match with another participant you would like to do a finer match-testing against. This may not occur for a while as the project grows in size.

There is some very good information on the front page, right hand side, of the Family Tree DNA site which is must reading, including this