14 August 2012

More than the Y chromosome

John Grenham's Irish Roots column for the Irish Times is a regular Monday morning stop for me. His latest, Swimmers or Spellers? is a case where he's off track IMHO. He writes "Only one kind of (genetic genealogy) test is unambiguously useful: a yDNA test ..." He continues "Comparing yDNA from Grenham males with roots in Roscommon and those from Kent can objectively identify when our most recent common ancestor lived."

While non-paternity events can confound things I don't argue with his example of the utility of a yDNA test. But his view on other genetic genealogy tests is rather behind the times; their value is already well proven.

Mitochondrial DNA testing, admittedly much less commonly useful as cases of ambiguity in the maternal line are comparatively rare, predates that for yDNA.

Instances are mounting daily of the value of autosomal testing in genealogy. Family Tree DNA's Family Finder, and 23andMe's Relative Finder both provide more than the percentage similarity to various geographical groups as mentioned in the Irish Roots article. While, like Grenham, many of us don't get particularly excited by our deep ancestry results these may provide clues to our ancestry on the other side of that impenetrable brick wall.

Likely Grenham has not experienced the thrill of serendipitously finding a DNA cousin, a member of a lost branch of the family tree, through autosomal DNA testing.

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