Kinship Data Benchmark for Multi-hop Reasoning

Tianda Sun, Dimitar Kazakov


Abstract
Multi-hop kinship reasoning is a natural testbed for LLM compositionality, but existing benchmarks (notably CLUTRR) cover only the descriptive Eskimo system. We introduce KinshipQA, a procedurally-generated benchmark covering seven anthropologically-documented kinship systems (Eskimo, Sudanese, Hawaiian, Iroquois, Dravidian, Crow, Omaha) and up to six reasoning hops, with a tunable simulator horizon that eliminates exact-instance pretraining overlap. Evaluating six LLMs, we find a 40.9% accuracy drop when reasoning shifts from biological multi-hop to culturally-marked classification on the five non-descriptive systems. The drop follows the anthropological hierarchy descriptive > bifurcate > generational > skewing, persists under chain-of-thought and few-shot prompting, and compounds with depth (10.6% at 5–6 hops). Humans given the override rule reach 89.0% versus 50.7% for LLMs, placing the failure in the model rather than the task. Two follow-up experiments suggest distinct contributors. A fictional-rule control swapping system labels and kin terms for invented strings raises accuracy by 6.1%, implicating familiar English surface forms. An in-context-rule probe prepending the override rule helps skewing systems (+17.1%) but hurts non-skewing systems whose baseline already exceeds ~60% (-13.4%), consistent with a missing skewing prior alongside rule interference where the model already has a working approximation.
Anthology ID:
2026.findings-emnlp.274
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
5767–5784
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.274/
DOI:
Bibkey:
Cite (ACL):
Tianda Sun and Dimitar Kazakov. 2026. Kinship Data Benchmark for Multi-hop Reasoning. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 5767–5784, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Kinship Data Benchmark for Multi-hop Reasoning (Sun & Kazakov, Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.274.pdf