DNA Basics

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.

Why use it in family history research?

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

• 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 testing

• 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

• 23 and Me
  • Autosomal (with paternal and maternal Haplogroups)
• AncestryDNA
  • Autosomal
• FamilyTree DNA
  • Autosomal Family Finder
  • mt-DNA
  • Y-DNA (37 markers through 111 markers)
• MyHeritage
  • Autosomal

Additional information

Hiring a DNA Testing Company Wiki page

International Society of Genetic Genealogy Wiki