I think you misread my words, rumncoke. The male line must be uninterrupted. So only one male ascendant is marked as carrier of the relevant chromosome - one of two male grandparents, one of four male great-grandparents, one of eight male great-great grandparents and so on.

Will, what you say, if correct, supports rather than diminishes the possibility that there is a heritable Celtic music culture. You are happy enough to refer to Celtic peoples, and happy enough to say that they were more frequently found on the western side of these islands. The people of these islands were not homogeneous. Whether that is a consequence of unforced migration from another place (in the south and west) as you assert, or as a result of forced migration driven from the east makes no difference to the fact that you assert of non-homogeneity. Why presuppose that the music of these islands was homogeneous?