Introduction to Genetic Genealogy: Dead People Can Talk After All

Note: the best way to absorb these lessons is to read them one at a time and follow the suggested links--not only will this help with "beginner's head spinning syndrome"-- it will allow you to absorb the material more fully. If you are an advanced beginner or intermediate you might find the terminology and background in Lesson 5 invaluable no matter which lessons are of interest. Also have a look at Lesson 11 which has a list of resources to help you including a new "Cheat Sheet File" category. If you really want to help your understanding and are considering a genetics course let me suggest a much better alternative. Either a refresher course in Statistics for those who haven't used it in a while or if you have never taken Statistics please consider an online course or one through your local community college. Even for the mathematically challenged grasping a few points on probability and statistical analysis is very worthwhile. It is applied math which makes it far more interesting, relevant and fun. You will use it every day. Really. Since I wrote this guide over four years ago many things constantly change. I try to keep up but it is nearly impossible.  The fundamentals should be the same.

I would like to share with you a quote from Israel Pickholtz which I think is fundamental to Genetic Genealogy

"No hard and fast rules.
Use your best judgement on your own work.
Keep your judgement out of other peoples’ work
Listen to and learn from the experience of others and apply judiciously.
Read the work of the best people in the field, but do not become part of a herd.
Support research – do it yourself if you know how."

What is Genetic Genealogy? Genealogy is simply the study of one's family tree or ancestry. Genetic genealogy uses DNA testing to determine the genetic relationship between individuals.

Why would someone want to use DNA for genealogy? There are many reasons but here are a few of the most common:

  • To learn more about one's ancestry

  • To confirm that one's family tree reflects one's actual ancestry

  • To confirm the relationship between two people

  • To validate a theory of where people came from

  • To break down a brick wall in one's genealogy research

  • To find relatives for those that were adopted, gave up a child for adoption or otherwise do not know their ancestry

  • To learn from which ancestor(s) certain traits were inherited

What is a a DNA test?

A DNA test is a tool that genealogists use for answering the questions above. There are three  basic types  kits being used. One involves spitting into a tube and the others are done by swabbing the inside of the cheek with a small brush. In the one the brush is left to dry in the other it is deposited in a tube. All are easy to use. The latter type has some advantages for those with little saliva production or those failing to get results with the other kind of test. They are also cheaper to mail overseas.

DNA tests for genealogical purposes do not involve needles, blood or urine. They are not the same tests used by law enforcement (CODIS) for crime identification purposes.

If you have not taken a DNA test yet but are thinking of doing so you may be interested in this research study

What is DNA?

The International Society of Genetic Genealogists (ISOGG) defines it:

"A polymeric molecule made of deoxyribonucleotides, hence the name deoxyribonucleic acid. Most often has the form of a "double 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. "

Translation: DNA is the molecule that encodes the genetic instructions for building and operating all living things. Humans are 99.9% genetically identical. That is a very important concept to remember. All the differences we see in the way people look, what diseases they may be prone to etc. come from the .1% difference. That doesn't seem like much until you realize that there are about THREE BILLION base pairs in which those differences may be expressed. The human genome is the complete set of human genetic information. It is located within the 23 pairs of chromosomes. Each half of the pair represents our mother or our father. These 23 chromosomes reside within the nucleus of our cells. There is also a small DNA molecule found within individual parts called mitochondria.

Simplified cell

Your DNA is in almost every cell that is you. In the above diagram the cell is the black circle. The nucleus is the green circle. The purple twisted matter within the cell nucleus is DNA. The orange circle is your mitochondria which also contain DNA.  The DNA replicated in the cells of your body is essentially your personal building and operating instructions given to you by your parents. But more than that it contains the encyclopedia of where you came from. It is the story of your ancestors told through the bits of DNA that they have passed down to you. It is that passing down, generation after generation that makes it so important to genealogists. That's what we mean by Dead People Can Talk. Your ancestors speak to you about their pasts via the DNA you still carry from them.

Note: All underlined terms will lead to the site being mentioned or a more technical explanation of the term at Wikipedia or the ISOGG Wiki. I am purposely keeping my use of genetic genealogist jargon sparse and definitions simple. As the lessons proceed and you become familiar with the terms they will be discussed in more detail. 

Note: If you are using Lessons out of order I highly suggest Lesson 5 to give you an ample vocabulary to work from.

More Resources:

Journey of Man: A Genetic Odyssey: YouTube version of this fascinating full length documentary

National Geographic The Human Family Tree You tube version---truly inspirational! Full length documentary

Faces of America 4 part series from PBS first two available here

Human Prehistory Videos from 23andMe. This series of animated videos (about 5 min each) are readily accessible even by children (7 and up)

Note: you may want to check your library for the above.

Lessons are constantly being revised as the genetic genealogy world changes rapidly. Feel free to email me with additions, corrections broken links etc. Clicking on the arrow next to the Beginners Guide to Genetic Genealogy (in the side bar) will reveal all available lessons. Reclicking will hide them from view. 

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