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|What Does It Test?
Y chromosome DNA tests are performed to determine if two or more men are biologically related through the paternal (father's) side of the family. It is commonly used where the alleged father is not available for testing. If the two men share the same Y chromosome DNA, then their Y-STR profile will be practically identical and they must be related. The Y chromosome is very distinctive and is passed from father to son and undergoes very little or no change in the process. However, the test cannot confirm HOW they are related, for example they could be brothers, uncle/nephew, grandfather/grandson or father/son.
This test should not be confused with a Paternal Ancestral Lineage Test - this is an ancestry gene test which checks for so-called SNP mutations and helps determine which ancestral haplogroup you descend from. Knowing your haplogroup will give you information about where your ancestors came from thousands of years ago and help to fill some gaps in any genealogy research you may have carried out on the family tree. What this cannot offer information on is inherited genetic disorders. This requires special genetic testing, ideally under the guidance of genetic counselors.
Who Uses This Test?
In some cases, it may simply be curiosity. Two men suspect they may be related but they would like to know for sure. In other instances it can be for legal purposes where an inheritance is involved and a man would like to confirm if the deceased man is for example, his father. If the man were alive paternity testing could confirm fatherhood. In the absence of the alleged father a Y chromosome test is sometimes taken to test other males such as an alleged brother, although as previously mentioned, it cannot confirm the exact nature of the relationship. Where it may be more useful is where two possible fathers are in question. Or if you are testing an alleged brother's DNA then the Y chromosome test could be used in conjunction with a sibling DNA test to strengthen the overall results.
Infidelity & Crime Investigation: Any stain left on a garment or at the scene of a crime can be checked for the presence of the male Y-chromosome. This will confirm the presence of a male. Additionally a DNA match may be made and the identity of the male discovered.
About The Y Chromosome
All humans have 23 pairs of chromosomes, and one of those chromosomes (the 23rd) determines the gender of the person. A female's 23rd pair of chromosomes is called X-X. The male's is called X-Y. When a child is conceived it inherits one chromosome from the mother, which is always an X. It inherits the other from the father which may be either an X or Y. If the child inherits the X she will be a girl and if a boy it’s a Y.
How Is The DNA Sample Collected?
Y chromosome tests are available for purchase online. A kit will be posted to your home which includes 4 simple buccal swabs, similar to cotton wool buds. The swabs should be rubbed on the inside cheek of the people to be tested (two swabs for each person). The swabs are then posted back to the lab for testing. Results are usually returned within 5 working days and can nearly always identify if a biological relationship exists. If required for legal purposes a chain of custody will need to be established. The test will then need to be carried out in the presence of a neutral party such as a doctor, nurse or diagnostic center.
This DNA technique was recently used to determine if President Thomas Jefferson (1743–1826) fathered Eston Hemings, a mixed-race slave. Researchers compared 19 genetic markers on the Y chromosome from 5 of Jefferson's descendants and one male line descendent from Hemings. The test revealed an identical genetic match leading The Thomas Jefferson Foundation to declare that there was a high probability that Jefferson did indeed father Hemings. He may very well have fathered the other 5 children of Sally Hemings, a mixed-slave in his ownership.
How Much Does It Cost?
The costs will depend on how many Y-DNA STR Markers are tested. Anywhere between 12 and 44 are common, the more markers investigated, the more accurate the results. Cheaper tests usually check fewer markers. Additionally, if you want the test for legal purposes, then the extra administration involved will increase the costs.
|12 Y-DNA STR Markers
|20 Y-DNA STR Markers
|44 Y-DNA STR Markers
Other Genetic Tests
• Grandparent DNA Testing
• Twin DNA Testing