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What do we mean by that? DNA

Today is the start of the week-long Institute of Genealogy and Historical Research (IGHR).

It’s the last year that IGHR will be at Samford University in Birmingham, Alabama; next year the Institute moves to the University of Georgia at Athens under the auspices of the Georgia Genealogical Society.

So… The Legal Genealogist is on the road today and will be jammed all week, teaching, learning, rejoicing in the first of this summer’s institutes that we love to call summer camp for genealogists.

But that doesn’t mean the blog will be silent.

Nope, we’ll use the time and the space to go over some terms we all need to understand and use as genealogists.

Today’s term, for DNA Sunday, is DNA.

DNA.defNow you’d think that we’d all know what DNA is by now, right?

I mean, we’re using it as a tool every day in genealogical research.

But do we really understand what those letters stand for, what they mean?

The glossary of the International Society of Genetic Genealogy says that deoxyribonucleic acid (DNA) is “A chemical consisting of a sequence of hundreds of millions of nucleotides found in the nuclei of cells containing the genetic information about an individual. It is shaped like a double-stranded helix, which consists of two paired DNA molecules and resembles a ladder that has been twisted. The ‘rungs’ of the ladder are made of base pairs, or nucleotides with complementary hydrogen bonding patterns.”1

Not terribly helpful?

Try this on: “any of various nucleic acids that are usually the molecular basis of heredity, are constructed of a double helix held together by hydrogen bonds between purine and pyrimidine bases which project inward from two chains containing alternate links of deoxyribose and phosphate, and that in eukaryotes are localized chiefly in cell nuclei.”2

No? (I didn’t think so…)

How about this one: Deoxyribonucleic acid or DNA is a molecule that contains the instructions an organism needs to develop, live and reproduce. These instructions are found inside every cell, and are passed down from parents to their children.3

Better, huh?

And then there’s this one:

DNA is material that governs inheritance of eye color, hair color, stature, bone density and many other human and animal traits. …

A strand of DNA is made up of tiny building-blocks. There are only four, different basic building-blocks. Scientists usually refer to these using four letters, A, T, G, and C. These four letters are short nicknames for more complicated building-block chemical names, but actually the letters (A,T, G and C) are used much more commonly than the chemical names …. Another term for DNA’s building blocks is the term, “bases.” A, T, G and C are bases. …

The sequence of bases (letters) can code for many properties of the body’s cells. The cells can read this code. …

The DNA code, or genetic code as it is called, is passed through the sperm and egg to the offspring. A single sperm cell contains about three billion bases consisting of A, T, G and C that follow each other in a well defined sequence along the strand of DNA. Each egg cell also contains three billion bases arranged in a well-defined sequence very similar, but not identical to the sperm.

… DNA… may vary from one individual to another. These DNA variations can be used to identify people or at least distinguish one person from another.4

Want a little more?

Check out these references:

• “What is DNA?”, Your Genome, Wellcome Genome Campus, UK.5

• “What is DNA?,” Genetics Home Reference, U.S. National Library of Medicine.6

• “What is DNA?,” Learn.Genetics, Genetic Science Learning Center, University of Utah.7


  1. ISOGG Wiki (, “Genetics Glossary,” entry for “Deoxyribonucleic acid (DNA),” rev. 29 Nov 2015.
  2. Merriam-Webster Online Dictionary ( : accessed 11 June 2016), “DNA.”
  3. Rachel Rettner, “DNA: Definition, Structure & Discovery,” Live Science, posted 6 June 2013 ( : accessed 11 June 2016).
  4. Donald E. Riley, “DNA Testing: An Introduction For Non-Scientists, An Illustrated Explanation,” Scientific Testimony: An Online Journal ( : accessed 11 June 2016).
  5. What is DNA?”, Your Genome, Wellcome Genome Campus ( accessed 11 June 2016).
  6. What is DNA?,” Genetics Home Reference, U.S. National Library of Medicine ( : accessed 11 June 2016).
  7. What is DNA?,” Learn.Genetics, Genetic Science Learning Center, University of Utah ( : accessed 11 June 2016).
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