Why do I have more than one result for an STR value? What is a multi-copy STR marker?

A multi-copy STR marker is one where there are multiple versions of the same STR in different locations on the Y-chromosome. Each STR copy [...]

What is the likelihood of a non-paternal event or false paternity?

We believe that the rate of unannounced adoption or false paternity is about 1 – 3% per generation and compounds each generation. When confirming [...]

What does each short tandem repeat (STR) marker mean?

By themselves, Y-chromosome DNA (Y-DNA) short tandem repeat (STR) markers from a Y-DNA test do not have any particular meaning. The value of testing [...]

Why don’t my Y-chromosome DNA (Y-DNA) test results show me percentages?

Your Y-chromosome DNA (Y-DNA) test results cannot be used to indicate your percentage of DNA from different ancestral groups. This is because tracing your [...]

If somebody doesn’t match me at 12 markers, how can they match me at a higher testing level?

Aside from their having matching turned off at the Y-DNA12 level, someone might match you at a higher testing level but not Y-DNA12 because [...]

If two men share a surname, how should the genetic distance at 111 Y-chromosome STR markers be interpreted?

In cultures where surnames are passed from father to son, there is additional evidence beyond a DNA match that two men who share a [...]