J1c3d Subclade

I have seen some claims that J1 is younger than J2. One even claimed it was just over 1,000 years old.

I checked the J1c3d [Tested] on ysearch.org. Some are as far apart as a genetic distance of 44 such as a 67 marker test between E43PY [Duncan] and KBZSZ [Leon-Guerrero].
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[Grigoriev]

The effect of population size on the accuracy of the estimate TMRCA, obtained by standard methods of population allele STR locus
Adamov, Karzhavin
The Russian Journal of Genetic Genealogy

Abstract

Model calculations the influence of characteristics of population...