GENEALOGY-DNA-L Archives

From:
Subject: [DNA] Dominant and recessive
Date: Mon, 19 Feb 2001 08:58:04 EST

In a message dated 2/18/2001 11:40:05 AM Pacific Standard Time,
writes:

> I am a genealogy researcher with little or no real DNA training. I note that
> the concept of Dominant and Recessive has disappeared from the dialogue of
> the experts. Is it not viable?
>

The terms dominant and recessive are still useful, but they apply to pairs of
genes. If a trait is dominant, one copy is sufficient for expression; if it's
recessive, both copies must be present.

I suspect the reason that we don't discuss these concepts here is that the
tests of genealogical interest use mtDNA and Y chromosome markers. They are
not testing for genes per se -- they are looking at parts of DNA which not
expressed, the so-called "junk" DNA. Also, the mtDNA and Y chromosome markers
don't come in pairs -- you have one variety of mtDNA, inherited from your
mother, and if you are male, one Y chromosome, inherited from your father. In
a sense, mtDNA and Y chromosomes automatically dominant.

We did have a short thread on whether it would be practical to have a
database of genetic traits which seem to be handed down over many
generations. If you want to search the archives, I think the keyword "quirks"
would bring up the messages. I'm still pondering if this is feasible -- I can
see lots of problems in defining traits, for example.

http://lists.rootsweb.com/index/other/Miscellaneous/GENEALOGY-DNA.html

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