Want to know HOW you are related to your cousin? When people are related, they share kinship with the other person and are descended from the same common ancestor. This means that blood relatives are direct descendants of a common ancestor, known as consanguinity.
When a common ancestor is known, you can use the following chart to determine the cousin relationship between two blood relatives. In our example, the grandchild and great grandchild are first cousins once removed, as shown on the red intersection of the chart. Click here to download a pdf printable of Cousin Relationship Chart. Blood relatives share common DNA which they inherited from a common ancestor. However, each generation shares LESS genetic material, the further away they are from the common ancestor.
This is because with each generation, new genes are brought into the hereditary line, with each birth of a new child. Distant relatives actually share very little DNA in common. So even if you are directly descended from George Washington, you really only share very little — almost no — DNA with him! You may randomly inherit more DNA from one side of your family tree, than from the other.
This is why you may look more like grandpa, than grandma! But when you inherit these chromosomes from your parents, they get shuffled up a little bit. This is a process called recombination. This mixing up is pretty random. Each time your parents have a child, the DNA will get shuffled up in slightly different ways. They might get slightly different pieces. To figure out how much DNA any two relatives have, we need to figure out how much DNA in common they inherited from each shared ancestor.
First cousins have two shared ancestors: one Grandmother and one Grandfather. So Grandchild and Aunt share But Grandchild and Cousin have two ancestors in common, Grandma and Grandpa. So you can add up the shared DNA that they inherited from each shared ancestor:.
But what about children of parents who are full siblings? Those children would be both full siblings and first cousins. In the real case of Cersei and Jaime, things get more complicated because Tywin and Joanna are first cousins. In this case, Joffrey, Tommen and Myrcella are siblings, first cousins, and third cousins!
We already know how much DNA siblings and first cousins would share, but what about third cousins? Doing similar calculations as above, you can figure out how much DNA someone shares with a great-great-grandfather:. Instead of the usual This is the same amount that you would share with a grandparent, a half sibling or an aunt or uncle. Most people know that we get half our DNA from our moms and half from our dads.
Here is a picture that shows this:. In this picture, the dad is in blue and the mom is in pink I know, stereotypical…but it is easy to remember. This is way oversimplified but is a useful way to think about things. As you can see, the child is half blue and half pink. She got half her DNA from her mom and half from her dad. So mom has half light blue and half light pink and dad has half dark blue and half dark pink. Unfortunately, this is too simple a way to explain your particular situation.
The same thing is true for each of your dads. The key thing we need to remember to explain this is that brothers and sisters do not get the same DNA from their moms and dads. To show this, we need to make our image a bit more realistic.
Lucky for you this just makes it harder for me to draw, not harder to understand. The first thing we need to do is to give each person two rectangles of different colors. These are supposed to represent that our DNA is organized into chromosomes. This is still too simple as we each have 23 pairs of chromosomes but it is a start. You can just take what we learn from the one pair I will be showing and expand it to the other 22 pairs. Well, to be a stickler, 21 of the pairs. The X and Y pair in males acts differently.
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