Archiver > GENEALOGY-DNA > 2010-03 > 1269382489

Subject: Re: [DNA] Family Finder results
Date: Tue, 23 Mar 2010 18:14:49 -0400

> For the life of me a centimorgan does not register.
> I'd like to think it is a unit of length of chromo..
Well, if you want a very rough estimate, then think of one cM as
somewhere in the ball park figure of 1 million bases.

There is a wide range. From my observations at 23andMe data, I see one
example of 28.5 cM as equal to 22 million base positions and on another
chromosome a block of 28.5 cM equals only 13 million bases. There is a
case of 11 cM = 7 million bases. I see another place where 48 cM = 56
million bases. In all these cases, the block is large enough to find
cousins who have ancestors in common within a genealogical time frame.

I like to think of it as poor shuffling in a game of cards. Each time
the cards are shuffled, there is a chance that after several
generations, there may still be a few cards in a particular sequence
still stuck together in a block. But some cards are just stickier than
others and resist scrambling.

Kathy J.

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