DNA Basics

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What is DNA?

Deoxyribonucleic acid (DNA) is a molecule found in nearly all human cells and contains the information for the development and function of all living organisms. A human DNA molecule is a double helix shaped like a twisted ladder. The human genome is the complete set of human genetic information found within 23 pairs of chromosomes for each person. Half of the chromosomes come from the father and half from the mother. These 23 chromosomes reside within the nucleus of the cells and some DNA is also found in the mitochondria.

Learn more about DNA and how it works

Why use it in family history research?

Some of the reasons you may want to use DNA in your family history research:

  • Break down a brick wall where paper records may not exist to solve the problem
  • Confirm the relationship between two people or families
  • Learn about deep ancestry and ethnicity
  • Locate the biological parents of adoptees or people who don't know their parentage
  • Verify ancestral lines found through paper records

DNA testing risks

May disclose information you weren’t expecting such as:

  • Adoptions
  • Illegitimacies
  • Non-paternal events (NPEs; where parentage may be unexpected)
  • Name changes

Types of DNA tests

  • atDNA (autosomal) males and females
  • mtDNA (mitochondrial DNA passed from a mother to each of her children) males and females
  • Y-DNA (DNA passed from father to son) males only

DNA testing companies

The companies listed below provide ethnicity results and match lists

  • 23 and Me - began in 2006
    • Autosomal (with paternal and maternal Haplogroups)
  • AncestryDNA - began DNA in 2012
    • Autosomal
  • FamilyTree DNA - began in 1999
    • Autosomal Family Finder
    • mt-DNA (with maternal Haplogroup)
    • Y-DNA (37 markers through 111 markers with paternal Haplogroup)
  • Living DNA - began 2017
    • Autosomal (with paternal and maternal Haplogroups)
  • MyHeritage - began 2016
    • Autosomal
  • For more information, go to Hiring a DNA Testing Company Wiki article.

Online Classes

Additional information

Facebook Groups

  • 23andMe Newbies - This is a group for those who are beginning genetic testing with 23andMe and discussing genealogy and health.
  • Africana Genetic Genealogy Consortium - This is a group for advanced-level exploration and discussion of African DNA research.
  • Ancestry DNA for Dummies - This group is to help understand Family research using DNA.
  • Autosomal DNA - This group talks about geographical and historical origins of your genetic markers.
  • DNA Detectives - From their Facebook group "The DNA Detectives group is focused on bringing together volunteers with genetic genealogy and searching experience with those seeking biological family -- adoptees, foundlings, donor-conceived individuals, unknown paternity and all other types of unknown parentage cases, near or far. This group is for members helping members and self-education."
  • DNA Tools - This group is for those interested in genetic genealogy DNA tools. Main sites discussed are DNAGedcom, Gedmatch AncestryDNA Chrome Extension and 23++ as well as new ideas for tools.
  • International Society of Genetic Genealogy (ISOGG) - From their Facebook group The mission of the International Society of Genetic Genealogy is to advocate for and educate about the use of genetics as a tool for genealogical research, and promote a supportive network for genetic genealogists."