Who Built This Model? Tracing LLM Lineage via Spectral Fingerprints in Weight Space

Open-weight large language models (LLMs) are increasingly developed through complex, multi-stage pipelines, leading to intricate lineage relationships that reflect model origin, ownership, and evolution. Understanding these relationships is important for model provenance, governance, and supply-chain integrity. In this work, we investigate the notion of LLM "biometrics" (analogous to human biometrics) to ask whether LLMs exhibit intrinsic fingerprints in weight space alone, without access to inp

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ethics.ai (7 August 2026), “Who Built This Model? Tracing LLM Lineage via Spectral Fingerprints in Weight Space,” evidence record 18338, https://ethics.ai/record/18338 (originally published by arXiv cs.LG).

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