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News and insights in the world of DNA and genetics for paternity, immigration and forensics

Archive for April, 2011 Monthly Archives

That’s right April 25th is National DNA Day.  It was proclaimed by both the US Senate and the House of Representative in 2003 and while you might not have the day off you might want to stop and think about just what DNA has done for us.

DNA Day is a remembrance of the day in 1953 when a gound breaking article on the structure of DNA was published as well as the the day that the Human Genome Project was completed in 2003.

DNA has made big changes in our lives whether we know it or not.  So this April take some time to think about DNA and some of it’s many uses:

1. In archeology DNA helps record genetic information of life on earth many centuries ago. This creates a data base that can be used to learn more about our planets past.

2. Genetic testing is used to determine the paternity or maternity of a child.

3. DNA testing can be used to help create a family tree or genealogical chart. Through genetic data bases one can trace lost relatives or find ancestors. Using both the Y chromosome and Mitochondrial DNA people can use DNA testing to establish ancestral lines (both remain unchanged for generations).

4. Prenatal genetic tests can help doctors determine whether or not the unborn fetus will have certain health problems.

5. DNA tests are also used to help solve murders and other crimes. In recent years many unsolved mysteries have been solved due to new ways of analysis as well as clearing many people found guilty of crimes that the did not commit.

6. DNA testing finds great use in the health field as DNA sometimes is the cause of rare medical conditions or heritable diseases.

7. Genetic testing is used in healths checks. For example it can be used to help determine the presence of viruses or cells that have mutated (causing cancer).

8. DNA tests are often used to reunite lost siblings or families or identify remains of the unknown. The genetics of a person leaves an indelible mark and this is used by police, military and authorities as well as individuals to confirm relationships.

9. DNA tests on new species or on material from outer space help scientists and researchers determine the origins of a species and where they stand with reference to known living forms.

As a DNA Relationship specialist, I have a lot of folks tell me that they assume that they are or are not related because of eye color, blood type or general appearance. Many people say things like “but the baby looks just like me”  or ” I have a different eye color than everyone else in my family so I must be someone else’s child”.  I am here to tell you that appearances are not always  a good indication of who the parent is.  I would like to  offer some answers to these questions or assumptions.

It is not possible to conclusively confirm paternity by using blood typing. The only thing you can establish is that the parents of the child had specific blood groups such as A, B, AB, or O. This does not eliminate any one else within those groups. As you can see below there are many possible combinations based on blood type:


As you can see, blood type does not answer conclusively the question of paternity. And as well, appearance also cannot definitively answer that question.  I have often heard, “she/he has brown eyes and both of her parents have blue eyes” so they are not sure who their parents are.  Eye color  cannot conclusively determine paternity. Eye color follows a polygenic inheritance pattern, and is probably controlled by 6 or more genes. Generally, these genes express themselves as one of 8 different eye colors. “Dark” is dominant at each of the 6 genes. The more dominant alleles present, the darker eye color appears. Therefore, eye color provides an even lower level of certainty than blood typing in determining paternity.

The same thing stands for hair color, let’s say red. It takes 2 carriers (Rr) to have a red-headed child.When a red hair carrier mates with a non-carrier, their children are not red headed, but some of their children will carry the red hair r allele. The frequency of the r alleles in the population in fact remains constant. We cannot easily tell if a person is a red hair carrier (Rr) without examining his/her extended family members’ hair colors or analyzing his/her MC1R gene.  However, we can reasonably expect the population of red hair carriers is much greater than that of the redheads. Even though there is no redhead in your immediate family, the chance that you are a carrier (Rr) is still quite high. It is estimated that as many as one in four Caucasians in the US might be a red hair carrier. Therefore, if parents don’t actually have red hair, if they both carry the red hair gene their children can have red hair.

Therefore, as it turns out, there are so many variables when it comes to eye, hair , blood type or looks the most conclusive way to discover the truth is to perform a paternity or maternity test. I hope this provided your with valuable answers  and addressed your questions or concerns.