What is the Shared DNA tool?
Our Shared DNA feature is a chromosome browser, which is a tool that can be used to view and explore which parts of your genome are shared with another person.
But what is a chromosome?
Most humans have 23 pairs of chromosomes (although this is not always the case, as with conditions such as Down Syndrome or Turner Syndrome). One chromosome in each pair is inherited from your mother, and one from your father. Because of a process called ‘recombination’, they are jumbled up and formed into a new pair that is unique to you.
How do I read the Shared DNA Chromosome Browser?
We use the 22 autosomal chromosomes to provide you with your matches - the 23rd chromosome isn’t used for this service - and each of the 22 chromosomes that make up your autosome are represented by a single row.
Dark blue segments highlight where on each chromosome you and your match have the same DNA. Each segment may be present on one or both copies of your chromosome.
In addition to the blue Shared DNA segments, you will see some grey striped areas. These represent parts of your DNA that are non-specific, meaning that they can be shared by people who aren’t related.
It’s important to note that while shared segments overlapping these striped regions are included in the cM total, they haven’t been used to estimate your relationship distance.
Switching to Table View shows you exactly which chromosomes are shared between you and your match.
Comparing this information to known matches can help you to narrow down where someone falls in your family tree.