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"Genealogy" and "Family History" by Michael Cummins

The use of the terms "genealogy" and "family history" are often used synonymously, but some offer a slight difference in definition. The Society of Genealogists describe genealogy as an "Establishment of a Pedigree by extracting evidence, from valid sources, of how one generation is connected to the next" and family history as "A biographical study of a genealogically proven family and of the community and country in which they lived".

I suppose that would make me more of a "Family Historian". We stand here today, on the shoulders of our ancestors. They struggled, succeeded, failed, loved and lost to give me and those I love a place to start. They handed down numerous traits and tools for our journey. I simply want to know more about them.

 

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Genetic genealogy

Your DNA contains information that has been passed down relatively unchanged from your early ancestors. Three DNA types are of particular interest:

  • Mitochondrial DNA, present in both females and males, is passed down with only minor mutations through the matrilineal (direct female) line. A mitochondrial DNA test (mtDNA test) traces a person's matrilineal or mother-line ancestry using the DNA in his or her mitochondria. mtDNA is passed down by the mother unchanged, to all her children, both male and female. A mitochondrial DNA test, can therefore be taken by both men and women. Males inherit mtDNA from their mother but do not pass it on to their children. They pass on Y-DNA to their sons but not their daughters. Thus, a mother passes her Mitochondiral DNA to her daughter and excepting minor copy errors (mutations) this remains more or less intact for thousands of years.
  • The Y-chromosome, present only in males, is also passed down with only minor mutations through the patrilineal (direct male) line from father to son, more or less intact for thousands of years. Women who wish to determine their direct paternal DNA ancestry can ask their father, brother, paternal uncle, paternal grandfather, or a cousin who shares the same surname lineage (the same Y-DNA) to take a test for them.
  • Autosomal DNA is a term used in genetic genealogy to describe DNA which is inherited from the autosomal chromosomes. An autosome is any of the non gender-specific numbered chromosomes, as opposed to the sex chromosomes. Humans have 22 pairs of autosomes and one pair of sex chromosomes (the X chromosome and the Y chromosome). Autosomes are numbered roughly in relation to their sizes. That is, Chromosome 1 has approximately 2,800 genes, while chromosome 22 has approximately 750 genes.

Haplogroup

Haplogroups pertain to a single line of descent, usually dating back thousands of years. As such, membership of a haplogroup, by any individual, relies on a relatively small proportion of the genetic material possessed by that individual.

Each haplogroup originates from, and remains part of, a preceding single haplogroup (or paragroup). As such, any related group of haplogroups may be precisely modelled as a nested hierarchy, in which each set (haplogroup) is also a subset of a single broader set (as opposed, that is, to biparental models, such as human family trees).

Haplogroups are normally identified by an initial letters of the alphabet, and refinements consist of additional number and letter combinations, such as (for example) A → A1 → A1a.

In human genetics, the haplogroups most commonly studied are Y-chromosome (Y-DNA) haplogroups and mitochondrial DNA (mtDNA) haplogroups, both of which can be used to define genetic populations. Y-DNA is passed solely along the patrilineal line, from father to son, while mtDNA is passed down the matrilineal line, from mother to offspring of both sexes. Neither recombines, and thus Y-DNA and mtDNA change only by chance mutation at each generation with no intermixture between parents' genetic material.

 

Handy Genealogy Links
DNA Related Websites
Y-DNA and mtDNA paths for males

 

Human Origins and Migration according to DNA