DNA-NEWBIE-L Archives

Archiver > DNA-NEWBIE > 2012-01 > 1327924301

From: "Patrick Cryans" <>
Subject: Re: [DNA-NEWBIE] Family connections
Date: Mon, 30 Jan 2012 11:51:41 -0000
References: <A1903B1E4B2248A89B6A449D17BABA60@PatrickPC><E861E89B7CC045D3B4EC8E6E641C1F41@NEWGAMES>

Hi Debbie,
Thank you for your reply. With regard my family i share the same Gt Gt
Grandfather (Paper Trail) with someone in Australia but he does not match
anyway near me at 37 markers different at least 6 markers.
So someone has a different father in our family, i suspect.
So going on that info i think there has been some external relationship
between our Gt Gt Grandfather 's generation and our fathers generation. We
are unable to find anyone else to test.
Going back to my original question which going by the chart indicates a 57.6
% chance of something occurring in this time frame, but which of us not the
family member ?
Patrick
-----Original Message-----
From: Debbie Kennett
Sent: Sunday, January 29, 2012 8:17 PM
To:
Subject: Re: [DNA-NEWBIE] Family connections

Hi Patrick

Everything is based on probabilities. You will share a common ancestor with
all your matches. Generally speaking the closer the match the more recent
the common ancestor but because mutations occur at random sometimes closer
cousins have more mutations and more distant cousins match very closely.

The easiest way to understand this is to use the TIP tool. Just click on the
little icon against the name of your match from your FTDNA personal page and
it will generate some percentages for the "time to the most recent common
ancestor". The TIP tool makes adjustments for the mutation rates of
individual markers, but here is a comparison I did on two men in one of my
projects who match on 36/37 markers:

Generations Percentage
4 57.86%
8 88.33%
12 97.21%
16 99.38%
20 99.87%
24 99.97%
28 99.99%

The probabilities simply give you a range within which the match could
occur. Over 97 out of 100 matches will fall within the last sixteen
generations, but that could still be well over 500 years ago.

For all practical purposes there's little point pursuing a match with
someone with a different surname unless you know that you both have
ancestors from the same geographical area. If they're in America and don't
where their surname originates then it's not really going to help you very
much.

Best wishes

Debbie Kennett

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