Test your knowledge of family relationships with my online quiz. After you press the "Get Results" button, correct answers will appear in green and incorrect answers will appear in red. You can go back and correct your answers and check your results again until you get all twenty correct. If you need help, go back and review my previous blog posts about family relationships. I've also included some tips at the end of this post. Good Luck!
When comparing two DNA matches, one thing I often do is, I think of the relationship from the point of view of two people in the same generation. This is tricky to explain. Take it one step at a time... For example, If Joe's grandparents are Fred's great-grandparents, then Joe is a generation older than Fred, right? So, if you don't know what to call that relationship, think of it from the point of view of Fred's parent. Fred's parent and Joe would be in the same generation. That means, Fred's parent and Joe have the same grandparents. When two people have the same grandparents, they are first cousins. Since Fred is a generation younger, he's a first cousin once removed. Remember, any cousin a generation older or younger than you is once removed. Two generations older or younger is twice removed.
The method mentioned above can come in handy with centimorgan numbers as well. If you don't have an understanding of centimorgans yet, don't worry. This will be explained more in future posts. In this example, if you know Fred is a generation younger and has a 450cM match to Joe, then you could guess that Fred's parent would have double the centimorgans, let's say 900cM. 450cM is a common first cousin once removed number. 900cM is a common first cousin number. So the numbers work out well in this case. Keep in mind, I'm using nice round numbers to simplify the example.
Another good tip is to create family trees. Visualizing the relationship always helps. Look at your tree compared to the tree of your DNA match. Many times your matches will not have complete trees made and you may have to figure out their families. A nice feature of Ancestry.com is, you can create as many trees as you want. Think about where you would be in the tree of your DNA match. The generation you are in is very important when figuring these things out. If you can figure out where your DNA match belongs in your tree and you add them in, Ancestry.com will even tell you the name of the relationship right in the tree.
Take good notes - Things can get really complex when investigating families. Trying to keep it all straight in your head can sometimes be impossible. The genealogy sites do have some features to help with this. Ancestry, for example, allows you to write notes right on your DNA match list. You can write personal info about the person, add color coded information, mark the person as paternal or maternal, and view common ancestors if you both have trees made.
You can use ethnicity to help determine relationships. I never rely on this completely, but your ethnicity chart can come in handy in certain situations. Keep in mind, ethnicity is only an estimate. It could be wrong in some cases, especially when it comes to small percentages. In the example shown below, we could find some valuable info. Take a look. The chart shows us a comparison of ethnicity between two DNA matches. Notice, John is about half German, and Kristy is about one fourth German. Maybe we know that John has two grandparents who are almost entirely German. That would explain his almost 50%. Maybe you were confused about Kristy's relationship and wondered if she had the same two grandparents. Her ethnicity chart would pretty much guarantee that she does not. You should still confirm it with other methods like centimorgans and shared matches, just to be sure. For this example, let's say Kristy had a 500cM match to John and one German line of John's tree is is the only place Kristy seems to be matching to. What would Kristy's likely relationship be? Easy, right? Half first cousin. They have one grandparent in common.
UPDATE: Since this posting, I've provided more information on generations and centimorgan numbers. If you're interested in learning more, a couple good posts to check out are: DNA Numbers Lesson and What Generation Am I In? In the numbers post I'll explain typical centimorgan values you can expect for various family relationships. The generations post deals with tricky situations when determining what generation you are in. Hopefully all these things will help you figure out your family. Feel free to ask for help if you need it.
Next, I'll discuss how to contact your DNA matches and birth parents.