Re: ANCESTRY QUESTION?

Stuart P. Derby (sderby@crick.ssctr.bcm.tmc.edu)
20 Jan 1995 00:03:20 GMT

hayesstw@risc1.unisa.ac.za (Steve Hayes) writes:
: colby@bio.bu.edu (Chris Colby) writes:
::
::Yes, but even in populations that preferentially outbreed, the lines
::intertwine. This is especially true of small populations (either
::geographically or socially isolated). Even if you go out of your
::way not to mate with a relative, but you live in what has been a
::small population for many generations, your mate will have _some_
::amount of relatedness to you.
:
:The number of avid genealogists is quite small, and in many societies people
:have no idea who they are related to beyond their great grandparents and
:their descendants. Even those societies that do keep track of ancestry
:usually keep track of one line only - direct patrilineal or matrilineal
:descent. So there are many fourth, fifth, sixth and seventh cousins who
:intermarry, and have no idea at all that they are related. Perhaps the
:increasing popularity of genealogy will make it possible for people to
:calculate an average of marriages to cousins at each generation.

In a fairly complete tree of 7-10 generations for a particular ancestor,
I've found 3 "in-breedings". One is a marriage of half-3rd cousins,
a shared GGgrandfather. The other is more complicated...

A=B C=D
| |
E == F

B and C are siblings, AND A and D are 5th cousins!!
So I guess E and F were "cousins plus" :-)

Then there's the couple who (serially) had the same step-mother:
no blood relationship though...

-Stu

-- 

-----------------------------------------------------------------------------

Stu Derby          |"Mr. Kelsey got into the dirt business in the usual way,

sderby@bcm.tmc.edu | studying international relations with an emphasis on

Baylor Coll. Med.  | Portugese-speaking countries..." WSJ,6/25/93,p.A1,col.4