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Todd Rowland

My Cousin’s Cousin’s Niece’s Grandfather Said to Just Ask Wolfram|Alpha

June 21, 2010 —
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One thing that is full of confusion is figuring out relationships. It can also be full of surprises, like the fact that Wolfram|Alpha can do it for you. If you follow this blog, you already know that Wolfram|Alpha can figure out and calculate lots of different things, including the moon and planets, and you are about to discover what it can tell you about your relationships.

Or at least relationships between your relatives. For instance, my cousin just had a sonโ€.

Wolfram|Alpha genealogy chart for "cousin's son"

We get a family tree, and it tells us that my relationship to my cousin’s son is that he is my first cousin once removed. Confusion resolved.

Like many other Wolfram|Alpha outputs, we get more than we may have expected. A few genealogical properties are related to historical laws, and a few are biological. The plots for sharing a Mendelian trait are given at the bottom after clicking More. This helps me understand how much I may have in common with my new first cousin once removed.

A dominant trait only requires one allele, while a recessive trait requires two. The other piece of information needed to say how likely it is to share a trait is how common it is in the general population. It is possible to share a trait accidentally, and for recessive traits one needs to get the other allele from the other parent. For my cousin’s son, not surprisingly, we see that the probability of sharing a genetic trait in common doesn’t seem to depend much on whether it is dominant or recessive. We are too distantly related to have much in common, and the probability of a shared trait between us depends primarily on the chance coming from the frequency in the general population.

It turns out that most traits are not simple like this, and involve more than one gene and so on, but this gives a general sense of how much we may have in common.

You probably know people who get confused about second cousins and so on, but there is also another category for relationship confusion.

Wolfram Alpha can compute the possible relationships given any sequence of relationships, not just the ones that people might use in real life. For instance, consider “my cousin’s cousin’s niece’s grandfatherโ€:Genealogy chart for "my cousin's cousin's niece's grandfather" in Wolfram|Alpha

The first pod shows the family tree based on what we just entered. It assumes that none of the people we mentioned are the same. Only the first few on the family tree are related in a traditional sense.

The next pod shows possible simplifications. I would never have figured this out myself, but if my cousin’s cousin was myself and the grandfather referred to was on the same side of my niece’s family as myself then her grandfather would be my sibling’s father, which would be my father. We get the other possible relationships, and also the neat statistic on the number of relationships that don’t have a traditional label like “father” such as the one pictured in the first pod.

Sometimes it’s best to let another do the relationship thinking. That’s thinking best left to Wolfram|Alpha.


This is awesome!
wolframalpha is the best!!

Posted by Arcsinh June 21, 2010 at 5:29 pm

Excellent. For those of us in the family history hobby, this is a great tool.

Posted by Gerald McDaniel June 21, 2010 at 6:22 pm

No has brother neither it mates but the son gives that man is the son give my father. Who is?

Posted by Jakub June 22, 2010 at 5:58 am

Dear Folks of Wolfram Alpha,

With all due respect, you need to change your name. It is the least user friendly name you could have selected. For people that are not geeks it inspires fear! Maybe you should shorten it to WA.

Eric Harmsen

Posted by Eric Harmsen June 22, 2010 at 10:42 am

    I completely agree. The name is not easily marketable to a wide audience. It sounds too complicated for a layperson.

    Posted by Alejandro July 8, 2010 at 1:02 pm

Eric Harmsen said:
With all due respect, you need to change your name. It is the least user friendly name you could have selected. For people that are not geeks it inspires fear! Maybe you should shorten it to WA.

I’m afraid I have to vehemently disagree with that. The name Wolfram|Alpha doesn’t inspire fear in any of the non-geeks I know, since they assume the word ‘wolfram’ has no special meaning and they’ve heard the word ‘alpha’ before. Also, shortening it to WA?? So you’re saying people should call it ‘waahhh’?

Posted by Hadee June 22, 2010 at 11:26 am

    brother’s brother need not be the same person, also daughter’s father’s sister, need not refer back to you, it can be your sister. Don’t assume, there is only one brother or sister for every person. ๐Ÿ˜›

    Posted by CleverButFlawed June 24, 2010 at 12:02 pm

There is one minor bug:

When going up through parents, Alpha automagically assumes the ancestor is the father’s. The line should start in the middle, instead.

Posted by RichiH June 24, 2010 at 3:35 am

    Thank you for bringing this to our attention! Our development team is looking into this further. Thanks!

    Posted by The Wolfram|Alpha Team July 8, 2010 at 5:21 pm

There are cultures where everyone that is not immediate family are cousins. I’m in favor of this system.

Posted by tudza June 24, 2010 at 4:23 am

No help for me. My cousin was adopted by my grandparents, so I am my cousin’s uncle and my uncle’s cousin. I was hoping for a name for that, but I’m either a first cousin once removed and/or an uncle

Posted by adam June 24, 2010 at 8:40 am

They can’t map out my family. Via marriage my dad is my cousin, my mom is my aunt, and I am my own first cousin once removed. ๐Ÿ˜‰

Posted by jsf June 24, 2010 at 10:51 am

Is there any way to input a GEDCOM file and have Alpha output a tree with the percent blood relationship on the tree?

Posted by wooac June 24, 2010 at 1:48 pm

You should support relationships like ex-husband and adopted daughter. I’ve been wondering what to call my mom’s ex-husband’s adopted daughter for years.

Posted by andrew June 25, 2010 at 5:36 pm

WOW—what a cool idea! Input a GEDCOM and have Wolfram/Alpha calculate the percent blood relationship on the tree. As a geneology buff I would love this. I think the implications for medicine could be astounding if W/A could also input a DNA sequence and provide mathematical probability of hereditary strengths and weaknesses in a blood line. Of course then we get into the ethics of knowledge and who does what with information. But W/A is fascinating and very helpful!

Posted by TTT June 25, 2010 at 11:51 pm

But it still can’t do half-relationships, like half-siblings.

Posted by Austin June 28, 2010 at 11:49 pm

I keep reading the name as wolfman alphra. LOL.

Posted by Cynthia August 5, 2010 at 8:46 pm

Wolfram Alpha says siblings share 25% of their DNA. It should say 50%.

Posted by Matt December 20, 2010 at 9:12 pm

[…] blogged last year about how Wolfram|Alpha can map family relations, which can certainly be more helpful the further your genealogical research takes you from the […]