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DNA newbie educational components

From ISOGG Wiki

Lesson 1: Basics of DNA, molecular biology and genetic genealogy

This site by Nancy Custer was my first introduction to genetic genealogy (after attending a DAR presentation about it, but I went home wanting to learn more).

It's a GREAT beginner's site! Read and post questions back to the list, especially if you get stuck or confused.

Lesson 2: DNA basics

What it looks like, who discovered it, uses and much more!

Lesson 3: Transmission

The paths Y-chromosome and mtDNA travels:

Charles Kerchner's charts are in a concise and easy-to-understand format which clearly illustrate the transmission of DNA from parent to child.

Lesson 4: DNA sampling

Bob Dorsey gives a detailed and humorous demonstration of how DNA is collected for sampling:

Lesson 5: DNA Processing

When Family Tree DNA receives your kit, it is placed in a batch which averages about 1,000 other kits. The batch is assigned a number and then sent to the lab for processing. For further information see:

  • PLEASE NOTE: All kits in an FTDNA batch will not return results at the same time.

Lesson 6: The results

Once your results are in, many people do not know what to do next or where to go to find answers.

Basically, your DNA results are a series of numbers that derive meaning when compared to others' results. For both Y-chromosome and mtDNA you receive the names and e-mails of those you match within the database. If you upload your results to a public database, such as or, then you may find that you have matches with people who have tested at other companies than the one which you've tested with. Sometimes, you may have to wait for the right person to test until you have a meaningful match.

Lesson 7: Mutations

As Wikipedia cites, mutations are a change in genetic material:

While the word has a negative connotation in our society, mutations in genetic genealogy are beneficial for identifying ancestral patterns within haplotypes (your DNA signature). If mutations cause you to be one, two, three, and sometimes even four off on a 37-marker match, it is still considered a match. (The four mismatches may be caused by another factor such as a RecLOH event, but we'll cover that later).

As Wikipedia also states, mutations can sometimes be caused by radiation, and other mutagens. For example: Pilots may have more mutations than average since they are exposed to atmospheric radiation.

Lesson 8: Mismatches

As referenced in Lesson 7, two people can be off by as much as four out of 37-markers and still be a match, dependent upon various circumstances.

For example: A male may have had a RecLOH event occur in a palindromic region (palindromes are the multi-copy markers i.e.: 385a, 385b, etc.) In such a case, the RecLOH event should be given the genetic distance of one as opposed to determining that two males are off by two.

Some families may have a higher instance of mutations where it may be necessary to order more than 37 or 43 markers to reveal whether the match is a true match or becomes farther apart.

In some cases, two males will mismatch on far more than 4 markers and are thus deemed to be unrelated. If their haplogroups differ, they most definitely are unrelated.

For further information on interpreting matches see the ISOGG Wiki page on matches.

Lesson 9: NPEs

Lesson 8 covered mismatches, and mismatches can sometimes be caused by NPEs. "NPE" is the acronym for non-paternity event which is a term used to apply to events that occurred in the past that may have been due to illegitimacy, adoption, fostering, etc. The name is actually a misnomer because no one has a "non-paternity" event in that everyone has a father. At the FTDNA Conference, Roberta Estes shared that she uses the term "undocumented adoptions" instead of using NPE, but unfortunately, NPE is a widespread term and probably here to stay.

NPEs are often the cause of mismatches. Sometimes, the NPE is known about ahead of time, and sometimes it is not.

Family members often question whether or not they are still family when an NPE has been revealed. An excellent essay on the topic has been compiled by the late Don Dickason: Familial and Genetic Descendancy; Conflict or Complement?

Lesson 10: Y-chromosome terminology

Since we're still mostly in the realm of the Y-chromosome, thought it would be good to cover some terminology.

Marker - A specific place on a chromosome with two or more forms, called alleles, the inheritance of which can be followed from one generation to the next. In genetic genealogy, this refers to non-coding Y-chromosome DNA. Numbers designate the individual DNA segments. Example: 393=13. This means at marker #393, your allele value is 13.

DYS - Acronym for DNA Y-chromosome Segment - The assigned number of a marker on a segment of the Y-chromosome. Example: DYS# 393

The acronym Y-STR stands for Y-chromosome Short Tandem Repeat. The number of times the sequence of bases repeat that determines the value of the marker. Example: Thirteen repeats of the same bases equals a value of '13'.

You will also sometimes see it referred to as just 'STR'. The whole string of numbers is known as a haplotype - some people also refer to this as a 'signature' or 'DNA signature'.

People often confuse a haplotype with a haplogroup and many do not know the difference. Even for myself, it was like a lightbulb going on when I learned the difference. A 'haplogroup' is a group of similar haplotypes that share a common ancestor with a SNP mutation.

Read Charles Kerchner's excellent "Haplotype vs. haplogroup":

Definitions source: Genetics Glossary

Lesson 11: Haplogroups & SNPs

From the Genetics Glossary:

Haplogroup - A group of similar haplotypes that share a common ancestor with a SNP mutation. Because a haplogroup consists of similar haplotypes, this is what makes it possible to predict a haplogroup. A SNP test confirms a haplogroup. Haplogroups are assigned letters of the alphabet, and refinements consist of additional number and letter combinations, Example: R1b1. Y-chromosome and mitochondrial DNA haplogroups have different haplogroup designations. Haplogroups pertain to your deep ancestral origins dating back thousands of years.

SNP - (pronounced "snip") - Acronym for single nucleotide polymorphism. A SNP test confirms your haplogroup by determining if a SNP has mutated from its derived or ancestral state. A SNP is usually found on a different area of the Y-chromosome than where the Y-STR markers are. Sometimes, a SNP may cause a null result on a marker.

Katherine's comments: Several DNA testing companies offer free haplogroup predictions. They are able to do this by comparing your haplotype to haplotypes in either a scientific database, proprietary database or both.

As defined above, haplogroups are your deep ancestral origins on just one direct line. While some might consider it a drawback to only be able to confirm ancestry on one direct line, the benefit of this is that with SNP confirmed results, the results are unambiguous. At the 3rd International Conference on Genetic Genealogy, Family Tree DNA debuted a new "SNP Assurance Program":

Family Tree DNA already SNP confirms ALL mtDNA results so further SNP confirmation is not required. (we'll go into this further in the mtDNA Educational Component)

To view an updated phylogenetic haplogroup tree, visit the ISOGG Y-DNA haplotree.

Lesson 12: Whit's Predictor

Lesson 11 covered haplogroups and SNPs and an important tool that should be mentioned at this point is Whit's Predictor

Whit Athey compiled the "Y-Haplogroup Predictor" as a tool to utilize by entering a haplotype which yields percentages for the most likely haplogroups. Try it out! Enjoy!

Other haplogroup predictors are now available. For details see Y-DNA tools.

Lesson 13: mtDNA Tutorial

From the Genetics Glossary: Mitochondrial DNA - Energy-releasing organelles located in the cytoplasm of cells, which contain their own DNA. Mitochondrial DNA is passed from mother to child, but only females continue to pass on their maternal mitochondria to their children.

Mitochondrial DNA is passed from a mother to her children, but only her daughters will pass on her mitochondrial DNA to their children.

More: What is mitochondrial DNA?

What mitochondrial DNA looks like

Family Tree DNA has a set of detailed FAQs on mtDNA that might as well be called "Everything you ever wanted to know about mtDNA". Ok... well, "almost" everything you want to know... it doesn't cover scenarios for using mtDNA with genealogy, but that's tomorrow's DNA Newbie Educational Component.

Lesson 14: mtDNA Tree

Mitochondrial DNA (mtDNA) is most often associated with deep ancestral origins since it mutates (changes) very slowly over time. Like Y-DNA haplogroups, mtDNA also has haplogroup designations. However, the letters for Y-DNA and mtDNA haplogroup designations do not correspond to each other. A 'K' in Y-DNA does not have the same ancestral origins as a 'K' in mtDNA.

Sometimes, you will see mtDNA haplogroups referred to with names, like 'Katrine' for 'K'. This naming convention originated in Bryan Sykes' book, The Seven Daughters of Eve.

mtDNA haplogroup H is the most common mtDNA haplogroup found in Europe. The mtDNA phylogenetic tree

An mtDNA cladogram compiled by Vincent Macaulay and Martin Richards

Lesson 15: mtDNA and genealogy - Part 1

Because our female ancestors did not keep their surnames, and we are fortunate if their first names, let alone their last names were recorded at all, mtDNA matches are not as easily revealed as Y-DNA matches. Another contributing factor may be that mtDNA mutates (changes) much more slowly than Y-DNA.

So how can we use mtDNA for genealogical purposes?

One of the best and most successful ways to use mtDNA is in the manner that Bill Hurst used it with the Kelly Sisters. He tested two known descendants, and concluded that the match confirmed indirect census and other records showing that Martha Kelly and Catherine Kelly were sisters and that their mother was Elizabeth Cummins Kelly. More on the Kelly Sisters match:

Lesson 16: mtDNA and genealogy - Part 2

Like Bill Hurst, another family used mtDNA to prove whether two lines were related. But this situation occurred much more recently in time and there was an adoption involved. The following mtDNA success story has been posted on the main ISOGG site courtesy of David Pitts, the Pitts Surname DNA Project Administrator:

"Emma's mother was unwed and barely 18 years old. When Emma was born, an old preacher abducted her and raised her as his own. He probably thought he was doing the right thing and later he claimed to have legally adopted her (e.g. 1930 census). Emma was raised with the preacher's surname and she never knew her real mother's name. Emma's daughter recently started to add some genealogical evidence such as census records to the family stories so that she could present an iron clad story of Emma's ancestry to her before she died. Despite her best efforts there was always some doubt that she had the right family. Emma's daughter did some research on the web and discovered that mtDNA might offer a tool to solve this puzzle once and for all. Using her own mtDNA and mtDNA from Emma's presumed Aunt Oleta (HVR1 & HVR2), she found an exact match, thus confirming the paper trail!"

Lesson 17: mtDNA and genealogy - Part 3

mtDNA results can also point someone in the direction they need to go in to research their line. This is what happened with Marie Rundquist when she tested through the National Geographic Genographic Project:

"I have been tested in the National Geographic Genographic project; my results have been transferred to Family Tree DNA. I am a member of Haplogroup A. My lineage is French/Cajun (through my mother's line); my Ancestral/Native routes are found in Nova Scotia, where a French settler, Rene Rimbault, married an Amerindian woman, known only as Anne Marie. It is through this union, that occurred in the mid-1600s, that my Native American and French lineage can be originally traced. I had no knowledge of my Amerindian lineage before participating in the Genographic project; I was totally knocked out of my chair when I read the results online. Mind you, I NEVER knew anything about the female line of my family until my mtDNA results came in as "Native American". This revelation caused my dad (and others) to get their DNA tested. I've learned a lot about my background since; and thankfully have met other folk who have helped me solve all these mysteries in my own family's background."

Read more about Marie's story at:

Lesson 18: mtDNA and genealogy - Part 4

A case where mtDNA was used to find a lost paper trail (much in the same way that we use Y-DNA) occurred as a result of Linda Thompson Jonas' watchful eye, good memory, and having the information available that she needed. Linda is the former Project Administrator of the U5 Haplogroup Project and she has people submit their pedigrees. She noticed a match which had similar geographic origins and with a little research, was able to take one woman's line back another 150 years! The full story appears here:

Haplogroup projects have varied and diverse goals. The haplogroup H project is another one that also posts pedigrees. For a complete list of mtDNA haplogroup projects, visit mtDNA haplogroup projects.

PLEASE NOTE: You need to have tested prior to know what your haplogroup is before you join a haplogroup project.

Lesson 19: Famous mtDNA

When your mtDNA matches someone famous, that does not mean that you are necessarily descended from them (especially a male since males do not pass their mother's mtDNA on to their children) but it does mean that you do share a common ancestor with them.

Click here to see if you have a famous genetic cousin:

Lesson 20: Famous DNA

Is there a famous (or infamous) person on the following site that YOU share a common ancestor with?

(Remember - haplogroup letter designations do not correspond between each other - an mtDNA K is not the same as a Y-DNA K)

Lesson 21: Famous DNA extraction

The extraction of ancient DNA is an expensive and complicated process which needs to be done in a specialist laboratory. Contamination with modern DNA has historically been a big problem, and early ancient DNA results should be viewed with skepticism. Ancient DNA has been transformed in recent years with the advent of next generation sequencing.