I only keep the best foal of each cross and then retire the parents once I've made my selection. Since each cross is only allowed one foal, this makes inbreeding impossible. If I do offer a foal out to the public, I have a little mark in the name to signify that relatives are out in the world so I know to check pedigrees if I breed that one to public stud or another I bought off another player that had multiple foals.

Thanks StormHeart! That is very helpful :D

I download the CSV data and then manually add parent IDs in new columns (it would be really helpful if the data included that info, I'm not sure why it doesn't TBH - I think it's been requested). Then when I use my foal calculator (that lets me pair horses together to see the results) it checks for potential inbreeding and gives me a warning.

Pippin that's great, I will definitely try that. I was trying to think of a way to do that so I'll play around with it. Would an equation somewhere along the lines of, if any values match (horse id #'s) in the row, then flag/xyz?

It gets a little tricky the more generations you have, because it needs to check the ids of the parents, grandparents, great grandparents etc against each other to see if there are any matches.

Are you using excel or google sheets?

Honestly I just gave up trying to avoid it. There's no downside to inbreeding, so now I just pair my horses according to best BS and TB. I started out trying to keep track, but once it got to three generations in it was pretty much impossible. 

I even have a few experimental lines now that are only descended from the same two parents (trying to get specific variations to pass on)

Circe, I'm using Google sheets for now. I was trying to have it cross check multiple columns for duplicates but I can only get it to successfully compare 1 column... I was hoping I could put a few numerical values in the same cell and separate them with a comma and have it still recognize them as individual values but I don't think that will work haha.

And Wireless mouse, I feel the same way sometimes!

Sorry Erasong! I keep switching between my accounts (Pippin / Circe / MillieMae < they're all mine) and I forget to change back before I answer.

But yes, that's the reason it's tricky. The checking has to be done multiple times across the generations. So if you have a mare & stallion that you want to pair, you'd have to check their parents (4 horses), their grandparents (8 horses), their great-grandparents (16 horses) and so on. Each further generation you go back doubles the number of horses to check.

I use excel, but I moved the way I do it into google sheets in case you wanted to take a look (I think it's right). If you make a copy you should be able to play around with it to see how it works. Feel free to let me know if you have questions :)

Hmm, that is tricky. I just made a copy, and I'll play around with it. That's quite a nifty setup, I love it!