Calculate Family Relationship from Genealogical Data

Question

I would like to be able to calculate the family relationship between two individuals in a family tree, given the following data schema (simplified from my actual data schema, on

Answer 1

You'll first need to calculate the Lowest Common Ancestor of both A and B. Call this Lowest Common Ancestor C.

Then calculate the distance in steps from C to A (CA) and C to B (CB). These values should be indexed into another table that determines the relationship based on these two values. For example:

CA      CB      Relation
1       2       uncle
2       1       nephew
2       2       cousin
0       1       father
0       2       grandfather

You might keep the basic relations in this table, and add "great-" for additional distances on certain relations like grandfather, ex.: (0, 3) = great-grandfather.

Hopefully this will point you in the right direction. Best of luck!

UPDATE: (I can't comment below your code, since I don't have the reputation yet.)

Your function aggrandize_relationships is a little off, I think. You can simplify it by prefixing "grand" if the offset is 1 or greater, then prefix "great-" (offset - 1) times. Your version might include the prefix "great grand great grand" for very distant relatives.(Not sure if I have the correct parameter in this explanation, but hopefully you get the gist of it. Also, no idea if your family tree is going that far back, but the point remains valid.)

UPDATE TOO: Sorry, the above is incorrect. I misread the default case, and thought it recursively called the function again. In my defense, I wasn't familiar with the "2nd great grandfather" notation, and always used "great great grandfather" myself. Code onward!!