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.
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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 of your matches will then [...]
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 limitations of microarray chip technology. [...]
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 chip.
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 segments and to determine relationships. [...]
The closeness of a mitochondrial DNA (mtDNA) match depends on the matching level. Matches at higher levels are more likely to be recent. The table below shows the expected time to a common ancestor with your exact matches. This time [...]
Yes. It is possible that a SNP will back mutate (change back). However, SNPs are slow changing. Thus, back mutations are uncommon.
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). For the immediate and close [...]
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 direction. The segment is therefore [...]
Yes, a higher number of compared Y-DNA STR markers does increase the power and accuracy for Time to Most Common Ancestor (TMRCA) calculation. However, there are diminishing returns after a certain number of markers. For exact matches who share a surname, [...]
The microarray chip used for Family Finder tests about .024% of your autosomal DNA.
If you have a Genealogical Data Communication (GEDCOM) file, you can upload it on your myFamilyTree page. To upload your GEDCOM file: Sign in to your myFTDNA account. Your myFTDNA page is displayed. On your myFTDNA page, click the myFamilyTree button. Your myFamilyTree page is [...]
The Y-chromosome DNA (Y-DNA) results chart headings are color coded in two ways. First, each testing level (Y-DNA1-12, Y-DNA13-25, Y-DNA26-37, Y-DNA38-67, and Y-DNA68-111) is coded with a different shade of blue. Second, the STR (short tandem repeat) markers that have faster mutation [...]
Bob, John, and I have the same Genetic Distance. However, when compared, we have different probabilities for sharing a common ancestor, for example, within eight generations. Why?
FTDNATiP™ uses both the number of mismatches and the mutation rates of individual markers in calculations. This means that although two men may have the same number of mismatches, they may not have the same predicted Time to Most Recent [...]
Using Family Finder results for genealogy is more challenging for individuals of Jewish ancestry because of a lack of genealogical records, surname changes, and frequent intermarriage. The lack of genealogical records means that finding the connection with even a third cousin [...]
The Filters & FTQL section is intended for our most advanced users. When you are ready, advanced filtering and FTQL query language increase the GAP's power. GAP Advanced Filters Advanced Filters and Family Tree Query Language (FTQL) are tools being [...]
The Family Finder test uses the Illumina OmniExpress microarray chip. The chip includes about 696,800 autosomal single nucleotide polymorphisms (SNPs). Note: After quality control improvements in chips manufactured on or after December 2012, Illumina reduced the number of SNPs on [...]
Family Finder detects your near and distant cousins by comparing your autosomal DNA with that of other Family Tree DNA customers. If two people share identical segments of DNA, they may share a recent ancestor. When the Family Finder program finds matching [...]
Our bioinformatics team treats centromeres as SNP Poor regions. We use a hard stop for matching across each centromere. This assures that DNA segments (blocks) are truly Identical by Descent (IBD) and not Identical by State (IBS). If you seem to have [...]