What is different about the STR markers DYS389I and DYS398II? Why is my DYS398II (DYS389-2) result at Family Tree DNA different from the Genographic Project?

The Y-chromosome DNA (Y-DNA) marker DYS389 is a single STR marker that has four parts: m, n, p, and q.

At Family Tree DNA we have [...]

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 [...]

What do the DYS, DYZ, and DYF prefixes on Y-DNA STR names mean?

The DYS, DYZ, and DYF prefixes are part of the scientific name for a short tandem repeat (STR) found on the Y chromosome. STR markers [...]

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 [...]