Grandfather Said to Just Ask Wolfram
One thing that is full of confusion is figuring out relationships. It can also be full of surprises, like the fact that WolframAlpha can do it for you. If you follow this blog, you already know that WolframAlpha 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 son».
Like many other WolframAlpha 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 son, not surprisingly, we see that the probability of sharing a genetic trait in common doesn 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.
The next pod shows possible simplifications. I would never have figured this out myself, but if my cousin cousin was myself and the grandfather referred to was on the same side of my niece family as myself then her grandfather would be my sibling father, which would be my father. We get the other possible relationships, and also the neat statistic on the number of relationships that don have a traditional label like such as the one pictured in the first pod.