I've spent the day trying to learn more about Y-DNA profiling and what
can be learned from the results. I am still interested in trying to
understand the CARROLL families of Sampson County, NC before 1800, but
I also need the information for another surname project.
As I was doing some searching on YSearch at
http://www.ysearch.org/
this morning, I entered the ID number I had been given for one person
with the CARROLL surname who has taken the 12 marker test. I searched
for individuals who matched all 12 markers exactly and had 0 as the
genetic distance allowed. I was surprised when 60 perfect matches
came up. That means that using 12 markers as the only criteria, that
individual could "prove" a very close relationship to those 60
persons. The real shocker was that all 61 of those persons had
different surnames!
As I thought about that, I wondered how many might have been affected
by
1. Illegitimacy
2. Adoption
3. Deliberate name change
Those three just couldn't explain that many people. Then I thought
something else. In the 1600's each settler was given 50 acres of land
as a "headright" for each person he brought to Virginia. Many families
in the British Isles, especially in Catholic Ireland, wanted a better
life for their many children than was available at home. (Remember
those wives hadn't yet been granted the right to even "just say NO!")
Some were glad to send their sons (and sometimes their daughters) as
apprentices to work for wealthy land owners and learn a trade. Some of
these children assumed the name of their master by legal adoption if a
civil authority existed in the area, and some assumed the name by
convenience. Many CARROLL's with lots of children lived in Catholic
Ireland. It won't be too surprising if other surnames match.
However, more importantly, it seems to me that this search shows the
necessity of using more than 12 markers for comparison. I believe to
establish any absolute "proof" of close kinship will take the 37
marker test.
Did I do this search correctly? Have others searched using an ID with
only 12 markers and found a lot of matches?
When I searched in the same manner using the ID # for another Carroll
using the 12 markers and 0 genetic distance, I got 17 matches. None of
these perfect matches had the CARROLL surname.
With another ID # there were 6 perfect matches using the 12 makers and
0 genetic distance. Again, none of these had the Carroll surname.
However, when I used 25 or 37 markers for this individual, there were
no perfect matches.
I hope we can soon find lots of Carrolls to send a DNA sample for all
37 markers, because I believe we will need a large data base before
many matches can be made. I also hope that not many will jump to the
wrong conclusions before there are more profiles with which to
compare.
Still learning,
Lura