What Do These DNA Results Mean?....
When your test results arrive - YIPPEE! - you will have a lot of information to sort through. And it can be overwhelming! Relax, take a deep breath, and remind yourself that this will be waiting for you later. Understanding the power of this wealth of family history at your fingertips takes time, as does learning to use it to build your "ancestories."
There are typically three categories on your results page - your settings for your account, an estimate of your ethnic makeup (more about that below), and a long list of DNA Matches. DNA Matches are our genealogy gold mine - these are other users in the company's database who match you, sorted from highest match to low confidence matches. Usually they are grouped into some category of possible relationships, but these are mostly generalized predictive ranges (e.g. 2nd-3rd cousins, 4th-6th cousins, etc.) for all but immediate family.
A quick recap from my last post; these tests look at specific sections of the autosomal DNA that makes up our 23 chromosomes, and we can inherit segments of this autosomal DNA from lots of different ancestors. Close relatives share a lot of DNA and segments on many of our chromosomes.
Look at the top match on your list and you likely will see someone very closely related to you - immediate family, an aunt or uncle, or perhaps one of your 1st cousins (1Cs). You'll also see some numbers, like total amount of match, number of segments and perhaps the size of the largest segment. The units are centiMorgans (cM) which measure the quantity of shared DNA. The higher the total, the more closely related we are.
While basic genetics predicts the amount that we should share based on the nature of the relationship (50% from each parent, 25% from each grandparent, 12.5% from each great-grandparent, etc.), in the real world we find that there is a LOT of variability. Dr. Blaine Bettinger has spent several years collecting relationship data from DNA testers with known relationships in his Shared cM Project. I use this excellent guide whenever I'm analyzing a new match.
Here are some common relationships, with typical and possible ranges of match amounts:
• Parents 3,487 cM (3,330 – 3,720)
• Siblings 2,629 cM (2,209 – 3,384)
• Grandparents 1,756 cM (1,156 – 2,311)
• Aunts/uncles/Nieces/nephews 1,750 cM (1,349 – 2,175)
• 1st cousins (1C) 874 cM (553 – 1,225)
• 1st cousin once removed (1C1R, your cousin's child or your parent's cousin) 439 cM (141 – 851)
• 2nd cousin (2Cs share a set of great-grandparents) 233 cM (46 – 515)
• 1C2R (your cousin's grandchild, or your grandparent's cousin) 229 cM (43 -531)
• 3rd cousin (3C) 74 cM (0 – 217)
Matching above threshold amounts means there is some relationship, but the ABSENCE of a match with a 3C or more distant relation does not confirm there is no relationship. The smaller the total amount of match, the more types of relationships are possible over a wider range of generations. This places significant limitations on what we can assume with smaller match amounts.
Now, about those Ethnicity Estimates - they are apparently a fabulously successful way to sell test kits! But confusion reigns supreme about the results; "I thought I was Irish, but instead I'm a Swede!"
These estimates generally are focused on more ancestral DNA shared with groups of common origins some 300 to 1,000 years ago, and it is an evolving and imprecise field. Each company has their own proprietary algorithms which they modify as their database of known users with verified genealogies grows. In short, it's amusing, and moderately useful at best. And bound to improve, but you probably shouldn't throw away all your careful collected family history based solely on an ethnicity mix that's different from your expectations.
NEXT UP: and for the flip side of this very exciting coin, What DON'T These Results tell us?...
There are typically three categories on your results page - your settings for your account, an estimate of your ethnic makeup (more about that below), and a long list of DNA Matches. DNA Matches are our genealogy gold mine - these are other users in the company's database who match you, sorted from highest match to low confidence matches. Usually they are grouped into some category of possible relationships, but these are mostly generalized predictive ranges (e.g. 2nd-3rd cousins, 4th-6th cousins, etc.) for all but immediate family.
A quick recap from my last post; these tests look at specific sections of the autosomal DNA that makes up our 23 chromosomes, and we can inherit segments of this autosomal DNA from lots of different ancestors. Close relatives share a lot of DNA and segments on many of our chromosomes.
Look at the top match on your list and you likely will see someone very closely related to you - immediate family, an aunt or uncle, or perhaps one of your 1st cousins (1Cs). You'll also see some numbers, like total amount of match, number of segments and perhaps the size of the largest segment. The units are centiMorgans (cM) which measure the quantity of shared DNA. The higher the total, the more closely related we are.
While basic genetics predicts the amount that we should share based on the nature of the relationship (50% from each parent, 25% from each grandparent, 12.5% from each great-grandparent, etc.), in the real world we find that there is a LOT of variability. Dr. Blaine Bettinger has spent several years collecting relationship data from DNA testers with known relationships in his Shared cM Project. I use this excellent guide whenever I'm analyzing a new match.
Here are some common relationships, with typical and possible ranges of match amounts:
• Parents 3,487 cM (3,330 – 3,720)
• Siblings 2,629 cM (2,209 – 3,384)
• Grandparents 1,756 cM (1,156 – 2,311)
• Aunts/uncles/Nieces/nephews 1,750 cM (1,349 – 2,175)
• 1st cousins (1C) 874 cM (553 – 1,225)
• 1st cousin once removed (1C1R, your cousin's child or your parent's cousin) 439 cM (141 – 851)
• 2nd cousin (2Cs share a set of great-grandparents) 233 cM (46 – 515)
• 1C2R (your cousin's grandchild, or your grandparent's cousin) 229 cM (43 -531)
• 3rd cousin (3C) 74 cM (0 – 217)
Matching above threshold amounts means there is some relationship, but the ABSENCE of a match with a 3C or more distant relation does not confirm there is no relationship. The smaller the total amount of match, the more types of relationships are possible over a wider range of generations. This places significant limitations on what we can assume with smaller match amounts.
Now, about those Ethnicity Estimates - they are apparently a fabulously successful way to sell test kits! But confusion reigns supreme about the results; "I thought I was Irish, but instead I'm a Swede!"
These estimates generally are focused on more ancestral DNA shared with groups of common origins some 300 to 1,000 years ago, and it is an evolving and imprecise field. Each company has their own proprietary algorithms which they modify as their database of known users with verified genealogies grows. In short, it's amusing, and moderately useful at best. And bound to improve, but you probably shouldn't throw away all your careful collected family history based solely on an ethnicity mix that's different from your expectations.
NEXT UP: and for the flip side of this very exciting coin, What DON'T These Results tell us?...
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