Genetic Genealogy in Practice: Chapter 1 Questions

 Genetic Genealogy in Practice by Blaine T. Bettinger, Debbie Parker Wayne. National Genealogical Socety; 2016

Chapter 1: Basic Genetics

Questions to which you will want to know the answers

What are the types of nuclear DNA?

  1. Autosomal
  2. Sex: X, Y

What is the other DNA which can be tested for genealogical purpose? 

Mitochondrial

Which test can be taken only by one sex? 

Y

If the mother of a family has died, which of her children can be tested for mitochondrial DNA? 

Any or all of them

From which parent do you get your Y dna

Father 

Your X? 

Men: mother. Women: both

What are the DNA variations tested for genealogical purposes? 

SNPs and STRs(Y). Both are often called "markers."

What is a SNP? 

Single nucleotide polymorphism

What is an STR? 

Short tandem repeat

How much of our DNA is identical to all other humans? 

99.9%

What is a DNA match? 

  • Enough matching DNA with a person above the threshold, usually 5-10 or 20 cM
  • People with matching DNA segment(s)

What is genetic distance? 

In mt & Y tests, the number of markers which are different between two testers. 

  • In mt tests, 0 distance sometimes means most recent common ancestor (MRCA) hundreds of years ago. Sometimes 1 or 2 difference can be close maternal relatives. 
  • In Y STR testing, a difference of 0 in a 111 test can be as close as brothers, and as far as the beginning of surnames.

What is a haplogroup? 

A main branch of the family tree, used with mt & Y test results. The more markers are tested, the closer one can get to a precise haplogroup. Although some mt and y haplogroups have similar notation, they are entirely different.


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