This article is the second in a series about the genetic genealogy workshop presented by the Fort Worth Genealogical Society. The first article was entitled, “Genetic genealogy another tool in ancestry research.”
Jane Buck has a background in biology and presented the workshop on behalf of Family Tree DNA.
Before she went into detail about the types of DNA tests available for genealogists, she presented what she called a “Primer on Genetic Inheritance and Understanding Different Types of DNA.”
“DNA is the blueprint for life,” Buck said, “like an instruction book for our cells so that they will know what to do.”
Every person receives DNA from their parents, who received DNA from their parents, and so on going back in time.
“Because we come from many ancestors, our DNA is a mixture of our ancestors’ DNA, but we have different types of DNA that we inherit in different ways,” Buck said.
She explained there are four major types of DNA, and three of them are most often used in genetic genealogy: Y-DNA, mtDNA, and autosomal DNA. It all begins with understanding the genetic makeup of the cell.
As it pertains to genealogy, it is important to know a cell is made up of cell membrane, cytoplasm, nucleus, chromosomes, organelles, mitochondria, and mtDNA.
The chromosomes are located in the nucleus of each cell. There are 23 pairs of chromosomes. Twenty-two of these pairs look the same in both males and females. The 23rd pair is called the sex chromosome and it looks different in males and in females.
The father’s sperm fertilizes the mother’s egg and the sperm will contribute either an X or a Y chromosome to determine the sex of the child. A female will have two X chromosomes because it receives one from each parent. A male will have one X chromosome from the mother and one Y chromosome from the father.
- Y-DNA is passed on by fathers to sons only. A Y-DNA test must be taken by a male subject.
- mtDNA is passed on to all children by their mothers. Each child receives an exact copy of their mother’s mtDNA. Anyone can take an mtDNA test.
- Autosomal DNA is a random mix of DNA from both parents. Each child in a family receives a slightly different blend of autosomal DNA. Anyone can take an autosomal DNA test.
The next article will go into more detail about DNA testing for genealogy.
Family Tree DNA was founded in 2000 and was the first company to develop commercial applications for genetic genealogy. Jane Buck began her genealogy hobby in 2005 and in 2010 joined Family Tree DNA to lead their customer service department. While Buck is no longer with the company and now works in environmental consulting, she still speaks to groups on behalf of Family Tree DNA.
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