What does coefficient of inbreeding actually measure?

COI quantifies the probability that two alleles in an offspring are copies of the same allele from a common ancestor. It requires counting every shared path through the pedigree—which is why duplicate ancestors in your query results are essential, not errors.

Will recursive CTEs in PostgreSQL work for descendant queries too?

Yes. Flip the logic: instead of joining on ancestors (sire_id and dam_id), join on offspring (any record where the starting animal's ID is listed as sire_id or dam_id). Same pattern, opposite direction.

Can I use this pattern for non-breeding pedigrees, like family genealogy?

Absolutely. The schema and queries work for human genealogy, historical records, anything with bilateral inheritance. The only change is adapting parent columns from sire_id/dam_id to mother_id/father_id.

☁️ Cloud & Databases

How One Developer Built a Production Pedigree Tree in PostgreSQL—And Why Your Genealogy App Is Probably Broken

A breeder's app tracking 200 animals in 9 days. The secret? Understanding why adjacency lists beat nested sets, and why your duplicates aren't a bug—they're inbreeding.

Open Source Beat Apr 03, 2026 6 min read 14 views

A PostgreSQL recursive CTE query tracing a multi-generation animal pedigree tree from one ancestor upward through four generations

⚡ Key Takeaways

Adjacency lists with self-referential foreign keys are the only schema that handles pedigrees correctly; nested sets and materialized paths fail at scale. 𝕏
Recursive CTEs are the right tool for multi-generation ancestor traversal—they're elegant, performant, and standardized across SQL databases. 𝕏
Duplicate ancestors in your pedigree query results aren't bugs; they're the signal for detecting inbreeding, and removing them corrupts your data. 𝕏
Closure tables lose to recursive CTEs for pedigrees because common ancestors create path explosion—the exact scenario where you most need efficiency. 𝕏

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#PostgreSQL recursive CTEs #adjacency list model #binary tree database queries #pedigree trees SQL #self-referential foreign keys

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Originally reported by Dev.to

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