Is it meaningful when two or more of my matches have a DNA segment or segments in the same location?
Yes. You may all share a DNA segment inherited from the same ancestor. However, you each inherited half of your DNA from each parent. Sharing with any two matches may be through a different parent. […]
If I have two matches with overlapping DNA segments, how will I know if they have those segments in common?
To tell if two or more of your matches have DNA segments in common, ask each to check for the other on their match list. If they are on each other’s match lists, they can […]
The centiMorgan (cM) values for DNA segments are measurements of how likely the segment is to recombine as it passes from parent to child. Segments with higher cM values have a greater probability of recombining […]
The Family Tree DNA bioinformatics team works with centiMorgan (cM) data from the International HapMap project. Current knowledge of centiMorgan values across the human genome comes from the International HapMap project testing. The project tested […]
Yes. Limitations in the number of global populations used and the number of samples tested in the International HapMap recombination rate studies limit what we know. SNP values at 12 locations in sequence Mother G […]
Are the areas with extremely high and low centiMorgan values related to SNP Rich and SNP Poor areas?
No. SNP Rich and SNP Poor areas are due to the number and location of single nucleotide polymorphims (SNPs) chosen by the microarray chip manufacturer. If the manufacturer includes many SNPs from an area on […]
The recombination rate across the human autosomal genome is highly variable. Therefore, DNA segments that are the same number of base pairs long may have much different centiMorgan (cM) values depending on their location.
If two people share part of the same DNA segment with me, will the centiMorgan value for each segment be proportional to how long the segments look?
Overlapping DNA Segments cM Matching on Chromosome 1 Match 1 Match 2 Non-Match 20.5 7.6 No. Part of a matching DNA segment may have a higher or lower centiMorgan (cM) value than the segment’s average. One […]
Is it more significant if two of my matches have identical start and stop points than if the segments simply overlap?
No. When two of your matches’ DNA segments share exact start and stop points, it is not more significant than when they simply overlap. There are two reasons for this. Both are due to current […]
You talk about matching DNA Segments. Is there a minimum number of matching segments in order for two people to be considered a match?
Although the number and size of matching DNA segments are considerations in calculating how two people are related, there is not a minimum number of segments for two people to be considered a match.
No. The Family Finder software does not use mitochondrial DNA results for matching or relatedness calculations. The Family Finder program uses only the autosomal SNP (single nucleotide polymorphism) test results from the Family Finder microarray chip.
No. The Family Finder software does not use Y-chromosome DNA (Y-DNA) results for matching or relatedness calculations. The Family Finder program uses only the autosomal SNP (single nucleotide polymorphism) test results from the Family Finder microarray […]
No. The Family Finder test does not currently use X-chromosome DNA (X-DNA) test results for matching purposes. The X chromosome follows a different inheritance pattern than the rest of your autosomal DNA. Therefore, it requires a […]
If your Y-chromosome DNA (Y-DNA) match is not on your Family Finder match list, it may be that the match did not take the Family Finder test. Matches do not work across databases. You may check […]
I have a close match. We cannot find any common names or ancestors on my Family Finder match list. Why can’t we?
It is both possible and reasonable for you not to have matches in common with a close cousin. For example, your relationship with your close cousin may be through your mother. However, your relationship to […]
I used a third-party tool to analyze my and a relative’s results. They are different from my Family Finder results. Why is this?
When you compare two people’s Family Finder results using third-party tools, it is common for there to be small differences. The FamilyTreeDNA Family Finder program uses a proprietary set of calculations to evaluate shared DNA […]
Family Finder raw results files are comma-separated-variable (CSV) files. We compress them into GZ (zipped) files for storage and portability. To extract the CSV file from the GZ file, you will need compression/decompression software to […]
No. The Family Finder test is not a legal paternity test. The Family Finder test is not AABB accredited and cannot be used in a court of law for paternity purposes. If you are interested in […]
How do my Family Finder match and I know on which line the connection took place? How can I tell on which side my matches are related (mother or father)?
It is not possible to tell from your Family Finder results if a match is from your mother’s side or your father’s side. This is because autosomal DNA recombines each generation. With an autosomal genetic […]
The Family Finder’s relationship ranges cover most possible relationships between two people. It takes into account several factors. These include the total number of shared DNA segments (blocks) and the total number of centiMorgans (cM). […]
Are there any exceptions or special cases in how our DNA is inherited that would affect my predicted relationship and range?
Yes. There are exceptions to the way inheritance normally works. One example is a type of mutation called an inversion. In an inversion, a segment of DNA has detached and then reattached in the reverse […]
We will send an email notification for any new Family Finder matches determined to be Immediate or Close matches. We do not send notifications for Family Finder matches that are more distant than 2nd cousin. Note […]
If your ancestors married their relatives, you may appear more closely related to your matches than you actually are. This is not uncommon. If you are part of an endogamous population, such as Ashkenazi Jews, […]
The Family Finder test traces all of your ancestral lines. It uses your autosomal DNA to identify relationships going back roughly five generations. This is different from our mitochondrial DNA (mtDNA) and Y-chromosome DNA (Y-DNA) tests. […]
Yes. Family Finder is able to tell a full sibling from a close cousin. Half siblings and first cousins, however, are harder to differentiate as they share roughly the same DNA in common. More distant […]
The microarray chip used for Family Finder tests about .024% of your autosomal DNA.
Yes. Men and women inherit autosomal DNA the same way. Therefore, the Family Finder test will detect matches to your relatives regardless of their biological sex.
To calculate the genealogical relationship between to people, compare the relationship to their common ancestor. It is often easiest to do this using a chart like the one below. For example, you and your relative […]
How many SNPs does the Family Finder program use to determine an Identical by Descent (IBD) segment?
The Family Finder program declares a DNA segment to be Identical by Descent (IBD) if it contains at least 500 matching SNPs (Single Nucleotide Polymorphism) in series. Note: This has not changed with the conversion […]