According to his east Galician death record, "Reuven" was born in 1805. His
third-great-grandson has done a 37-marker Y-chromosome test.

The known children of "Shimon" were born >from the mid- or late-1840s so
Shimon was probably born latest 1825, but 1820 or earlier may be a better
guess. His second-great-grandson has done a 67-marker Y-chromosome
test.

For 37 markers, these two descendants are exact matches.

My two questions are a) what can we deduce (and to what degree of
confidence) about the relationship between Reuven and Shimon and b) how
useful would it be to upgrade the tests.

Although it is possible that Reuven is Shimon's father, it seems more
likely that the closest they can be is brothers. With the Y-chromosome
match we have, how likely is it that they are in fact brothers, rather
than uncle-nephew, first or second cousins etc?

Let me add here that we have autosomal tests for a second-great-
granddaughter of Reuven and two great-grandchildren of Shimon (first
cousins). One of those two comparisons comes out "supposed second
cousin" and the other "supposed third cousin."

Israel Pickholtz
Jerusalem
(blogging weekly at http://allmyforeparents.blogspot.com )