From that point on, pedigree collapse becomes a stronger factor than the normal upward x2 multiplier, and the tree converges inwards. The simplest way to think about it is that every stranger in the world is a cousin of yours, and the only question is how distant a cousin they are.
The degree of cousin first, second, etc. For first cousins, you only have to go back two generations to hit your common grandparents. For second cousins, you have to go back three generations to your common great-grandparents. Since a lot of people get confused about cousin definitions, I made a little chart illustrating what a second cousin is.
So notice that for you and your second cousin, A your parent is a first cousin of their parent, B you have grandparents that are siblings, and C their parents are your common great-grandparents. For third cousins, everything just goes up a level—your parents are second cousins, your grandparents are first cousins, your great-grandparents are siblings, and you have a common pair of great-great-grandparents. A straight second, third, or fourth cousin must be on your same generation level.
The number of cousins you have grows exponentially as the degree of distance goes up. You may have a small number of first cousins, but you likely have hundreds of third cousins, thousands of fifth cousins, and over a million eighth cousins. Because I got a little obsessed with this concept while doing this post, I decided to roll up the nerd sleeves and figured out a formula for this:.
I calculated some examples below:. Most interesting to me is that these numbers go up so exponentially that taking the world average for number of children per family 2. The other way to look at this is from the top down and see how quickly the distance of relation is magnified as generations move down—while you and your sibling grew up in the same house, your kids will be cousins who might or might not be friends and your grandkids might barely know each other. In its first couple hundred years, before expanding into the thousands, it might look something like this:.
Little Telia, born right around the year , is as much a mystery to you as your ancestors from the early s up above. Wait But Why posts regularly. If you like this, check out Meet your ancestors all of them , Your life in weeks , and What makes you you. By providing your email, you agree to the Quartz Privacy Policy. Skip to navigation Skip to content. Discover Membership. And third cousins share the same great-great-grandparents. First, second, and third cousins and so on are the same number of generations removed from the common ancestor the grandparent as one another for example, first cousins are both two generations removed from the grandparents they share, and second cousins are both three generations removed from the grandparents they share.
In cousin relationships, the term removed indicates the separation of a generation. Like removed, the terms great and grand indicate the separation of generations. With grandparents, grandchildren, aunts and uncles, and nieces and nephews, the generation two generations away gets the designation grand, while further generations have great tacked on. For example, your grandfather is two generations away from you, and your great-grandfather is three generations away.
Your grand-niece the child of your niece or nephew is two generations away from you, and your great-grand-niece the grandchild of your niece or nephew is three generations away.
People are half siblings when they share one biological parent and not the other. All other half relationships stem from an original half sibling relationship. Your half nephew is the son of your half sibling; your half great-aunt is the grandparent of your parent's half sibling; the children of half siblings are half cousins.
Download Cousin Chart. The number associated with your cousin has to do with how many generations away your common ancestor is. For example:. However, keep in mind that this trick only works if you are both the same number of generations removed from the common ancestor. Sometimes you and your cousin may share a common ancestor,but you each call this ancestor something different. The number before "removed" will always represent the number of generations you are separated "removed" from the cousin.
You, your siblings, and your first, second,and third cousins are all of the same generation. This is because your parents and their generation are 1 above yours. This pattern continues throughout each generation. So, for example, a first cousin once removed is either the child of your first cousin or the parent of your second cousin.
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