Linda,
The mutations each subject has only to himself did happen later, in some
generation after Peter I, but before themselves. We don't know, yet, where.
The values that they all share had to have occurred before Peter I because those
were the values he transmitted. Peter might have been carrying, at most, one
new mutation from his father. We won't know that until we've hooked up with his
originating family.
These subsequent mutations, in our tested subjects, could have happened in any
generation, even the current one. I have twice had reason to test brothers in
my family. In one case, the brothers matched 67/67, but in the other, they
matched 66/67. In the latter case, a mutation occurred between the father and
one of his sons. We know which one because one of the brothers matches his
cousins, while the other is off by that one mutation. In other words, one of
the brothers is modal at that marker (same value as his seven tested cousins),
while the other brother is unique in the family for that marker.
The mutation occurs during "spermatogenesis," the biological process whereby an
undifferentiated cell in the father's testicle is transformed into a mature
sperm (independent, with a means of propulsion). Just that one sperm carries
the mutation, so it is transmitted to just one son. From then on, the son
bearing the mutation will pass it on to all of his sons. That's how we're able
to pin-point where a mutation took place, provided we have enough test subjects.
The odds against the same mutation happening twice in sperm transmitted by one
father are so astromical that it is taken as a given that any particular
mutation is a one-time event transmitted to only one son. The odds against one
father having more than one son with *any* mutation, much less the same
mutation, are also astronomical -- unless the father works in a nuclear power
plant... Seriously, mutations are fundamentally rare events, which is the
reason this method works.
Diana
P.S. There's something to be said for, ultimately, testing all of your living
male blood relatives. You don't know what you'll turn up. Maybe nothing
unexpected, but that's a nice outcome, too.
-----Original Message-----
From: carrico-dna-bounces(a)rootsweb.com On Behalf Of Linda Boorom
Sent: Monday, August 20, 2007 1:56 PM
To: carrico-dna(a)rootsweb.com
Subject: Re: [CARRICO-DNA] Node Chart for Peter CARRICO I
I have, I guess, 2 questions.
Is it not possible that some of these mutations took place in more recent
generations?
If so, I understand the need to have more "cousins" tested,
as even with first
cousins, there could
be a slight difference?
OK, so I have three (3) questions :-)
When a mutation takes place, does it take place in all sons? For example, I
have 3
brothers. If all
3 brothers were tested as well as my father, if the mutation took
place in my
father's offspring (&
not in him), would all 3 brother's have the same mutation, or
could just one
of the 3?
Just curious.