Predicted ∂95 Dispersion at 5 and 15 generations

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Contents 1 Background 2 Figure	This is one of a series of articles on Genealogical Methods, prepared in association with The Tapestry. See Index for a list of related articles.

Background

"Similarity" is a measure of the extent to which a descendants YDNA haplotype matches that of one of their ancestors. If only a few generations have passed the descendant haplotype will be very similar, if not identical to the ancestral haplotype. If a substantial number of generations have passed, some descendants will differ from the ancestral haplotype by a substantial amount. The difference between the ancestral haplotype and that of a descendant can be expressed as "Similarity" which shows the fraction of the markers which the ancestral form and the descendant form share the same marker values. If a 37 marker get is taken, and the descendant differs from the ancestral form by exactly 1 marker, the "similarity" would be 36/37=97.3%; This can also be expressed as dissimilarity: 1/37=2.7%.

Given an initial "seed" haplotype, the haplotypes of descendants can be predicted based on marker specific mutation rates after a specified number of generations. The metric ∂95 is used to indicate the YDNA similarity acceptance criteria that would be needed to "capture" 95% of the descendants after a certain number of generations.

Figure