Andy Lee
2 min
Updated: Feb 15, 2021
When reviewing your DNA match results, have you ever wondered where exactly a DNA segment starts and ends? Have you also wondered whether or not that's important?
Many genetic genealogists use DNA matching segments to determine if individuals share a common ancestor.
For example, Devon and her 2nd Cousin, David, share the same start point and endpoint on Chromosome 12. She can then use that segment to see what other DNA cousins have the same or an overlapping DNA segment in the same location. Then genetic triangulation occurs, and these DNA matches share a common ancestor. The only question is who.
However, what happens when 23andMe and MyHeritage don't report the same start and end point?
What happens if you import your data from Ancestry, 23andMe, MyHeritage, or other tests into GEDmatch, and your start and end points vary? Can you be confident in your triangulation efforts and relationship conclusions?
In this video, Andy uses his and his brother's data to compare 23andMe, MyHeritage, and GEDmatch, focusing primarily on one chromosome and the start and endpoints each company reports.
As you watch this video, you'll see the following chart.
Click on the image above to expand it to see a clear view of the table Andy discusses.
In this video, Andy will review the:
inconsistencies between each company
possible reasons for the inconsistencies
why the inconsistences don't necessarily matter
whether start and endpoint comparisons are useful.