This is an example of four people who match me on chromosome 4 using data stored in FamilyTreeDNA, a commercial service. The four differently colored bands on the chromosome map numbered 4 is the indication. FTDNA's chromosome browser is a way of visualizing the match. I supplied FTDNA with a copy of my Ancestry test and for a fee, they entered it into their database. Currently, I have 2545 matches on FTDNA.
I did the original test on Ancestry which lists about 30,000 of which 1125 are labeled 4th cousin or closer. I also loaded the test on GEDmatch which is a free site (unless you wish to use advanced utilities, which I do). There I have nearly 10,000 single matches and 4,000 triangulated matches.
I have written software that analyzes the output from GEDmatch. Using that software, I have determined that two of the people listed in the chart are in GEDmatch and FTDNA and two are only in GEDmatch. My software tells me that there are 31 more people in GEDmatch have the same match. And I know that my maternal aunt matches more than 31 in the same place on the same chromosome.
