All human beings, as well as most other living things, have DNA. In fact, according to biologists, it is DNA that makes each and every species special. DNA is responsible for determining physical characteristics of human beings such as the color of the eyes, height or even color of the hair.
Numerous studies have established that an estimated 99.9% of the DNA in any two individuals is the same. The remaining 0.1% of the DNA is called the genetic marker, and it is the part of DNA that makes people unique.
However, studies have established that identical twins also have identical DNA genetic markers. People who are closely related are also likely to have similarities in their genetic markers. DNA testing performs the task of identifying individuals as well as to fulfill several other purposes. For example, to determine if a person is the biological parent of a certain child.
DNA tests can also be used to determine an individual’s ancestry. While most people are familiar with forensic DNA testing, few are familiar with the types of tests that are available for the sole purpose of genealogy.
Before delving into the different types of DNA tests that are available for genealogical purposes, it would be important first to understand what it is inside a human cell:
Human cells contain a nucleus in the center. The nucleus contains autosomal DNA. Autosomal DNA comprises 22 pairs of chromosomes which do not play a role in gender. The nucleus also contains sex chromosomes; XX for ladies and XY for males. The cytoplasm contains mitochondrial DNA, which is the area surrounding the nucleus. Mitochondrial DNA passes on from the mother to the child.
This type of DNA testing is without doubt one of the most popular. This test attempts to track the Y-chromosome which is normally passed down from father to son. It would be important to note that since females do not have the Y-chromosome they cannot be tested using this DNA test.
This test determines whether two individuals are related (the closer the match between the individuals’ DNA, the closer the genealogical relation). This test is called Short Tandem Repeat (STR) Test. Secondly, Y-DNA tests determine an individual’s ancestry through a Single Nucleotide Polymorphism (SNP) test.
The test also helps to determine the possible haplogroup that an individual belongs to hence defining the individual’s ancestry as African, European, Asian or Indian among others.
Mitochondrial DNA Test
Everyone has mitochondrial DNA, inherited from the mother. Because of this, anyone, irrespective of gender, can undertake this form of DNA testing. However, it would be important to note that males cannot pass the mitochondrial DNA to their children.
Mt-DNA tests are used to trace down an individual’s maternal line. The basis of the test is that mitochondrial DNA is normally passed from mother to sibling without any mixing. An exact match of DNA samples would, therefore, be a clear indication of shared ancestry.
Nevertheless, these tests cannot tell you how recent a common ancestor was. One setback of Mt-DNA tests is that they are more difficult for genealogical purposes because the surnames of women change. This makes it harder to make genealogical connections between individuals.
However, since these DNA tests can also be used to identify haplogroups, they can be used to trace one’s ethnic origins.
Autosomal DNA Test
This kind of DNA testing is concerned with analyzing the 22 pairs of chromosomes contained in autosomal DNA. Every single individual inherits autosomal DNA directly from parents.
In addition to that, the autosomal DNA also contains random segments and sequences inherited from older ancestors such as grandparents and great-great-grandparents. DNA matches are normally stronger for recent ancestry and individuals who are closely related. Nonetheless, it is possible to trace down DNA matches to up to 5 generations or further in some cases.
Anyone can take an autosomal DNA test regardless of age or gender. Some experts suggest that autosomal DNA tests can uncover an individual’s ancestral heritage more accurately than other tests.
This is because it analyzes an individual’s heritage on both the paternal and maternal lines at the same time. Indeed, autosomal DNA tests can be used to match individuals with all their relatives from multiple ancestral lines.