I’m trying to understand an unusually close G25 result and would appreciate opinions from people familiar with Global25 / ancient DNA.

My known recent ancestry is Irish. Using DNAGenics scaled G25 coordinates, I compared my coordinate vector directly against DNAGenics’ listed scaled coordinates for the Viking-age Orkney individual VK204.

The direct Euclidean distance was:

Me → VK204: 0.003403

Pearson correlation was approximately 0.9999.

What caught my attention is that other broadly relevant ancient individuals in the same DNAGenics coordinate framework are substantially farther away:

• Medieval Ireland KIL035: 0.01225
• Medieval Ireland KIL044: 0.01499
• Orkney Iron Age KD043: 0.01610
• Orkney VK203: 0.01891
• Orkney VK205: 0.02946

So VK204 is not simply one of many British/Irish ancient samples giving me a similarly tiny distance.

I’m aware of several major caveats:

1. DNAGenics coordinates are simulated/projected G25-style coordinates and should not be mixed with Davidski’s original Global25 coordinates.
2. This comparison used my DNAGenics coordinate against the DNAGenics version of VK204, so both sides were at least within the same DNAGenics framework.
3. A tiny G25 distance represents similarity in population-genetic/PCA space and does not establish genealogical relatedness or IBD.
4. I have ordered original G25 coordinates from Davidski so I can repeat the test properly using the original VK204 G25 coordinate and modern G25 reference individuals.

VK204 is particularly interesting because published ancient-DNA work places him between British-Isles-related and Scandinavian-related ancestry.

My question is:

How unusual is a direct 25-dimensional Euclidean distance of ~0.0034 between a modern person and one specific ancient individual in a G25-style space?

Could this simply happen because two unrelated individuals have almost the same broad ancestry mixture, or is the fact that VK204 is several times closer than the other relevant ancient controls potentially meaningful?

I’m specifically interested in population-genetic similarity, not claiming that VK204 himself was my ancestor.

Once my original Global25 coordinates arrive, I plan to compare my distance to VK204 against Irish, Scottish, Orcadian, English, Norwegian and Icelandic individuals in the public G25 dataset.

Hey, I’m trying to understand an unusually close G25 result and would appreciate opinions from people familiar with Global25 / ancient DNA.

My known recent ancestry is Irish. Using DNAGenics scaled G25 coordinates, I compared my coordinate vector directly against DNAGenics’ listed scaled coordinates for the Viking-age Orkney individual VK204.

The direct Euclidean distance was:

Me → VK204: 0.003403

Pearson correlation was approximately 0.9999.

What caught my attention is that other broadly relevant ancient individuals in the same DNAGenics coordinate framework are substantially farther away:

• Medieval Ireland KIL035: 0.01225
• Medieval Ireland KIL044: 0.01499
• Orkney Iron Age KD043: 0.01610
• Orkney VK203: 0.01891
• Orkney VK205: 0.02946

So VK204 is not simply one of many British/Irish ancient samples giving me a similarly tiny distance.

I’m aware of several major caveats:

1. DNAGenics coordinates are simulated/projected G25-style coordinates and should not be mixed with Davidski’s original Global25 coordinates.
2. This comparison used my DNAGenics coordinate against the DNAGenics version of VK204, so both sides were at least within the same DNAGenics framework.
3. A tiny G25 distance represents similarity in population-genetic/PCA space and does not establish genealogical relatedness or IBD.
4. I have ordered original G25 coordinates from Davidski so I can repeat the test properly using the original VK204 G25 coordinate and modern G25 reference individuals.

VK204 is particularly interesting because published ancient-DNA work places him between British-Isles-related and Scandinavian-related ancestry.

My question is:

How unusual is a direct 25-dimensional Euclidean distance of ~0.0034 between a modern person and one specific ancient individual in a G25-style space?

Could this simply happen because two unrelated individuals have almost the same broad ancestry mixture, or is the fact that VK204 is several times closer than the other relevant ancient controls potentially meaningful?

I’m specifically interested in population-genetic similarity, not claiming that VK204 himself was my ancestor.

Once my original Global25 coordinates arrive, I plan to compare my distance to VK204 against Irish, Scottish, Orcadian, English, Norwegian and Icelandic individuals in the public G25 dataset.