Birds of a feather is identity, not selection: identity-admiration edges assort by neurotype while blind citation and institutional mentorship edges do not

Are 'birds of a feather' effects on neurotype a free-selection law or a narrower identity mechanism? On a cross-civilization database of 5,525 historical figures we construct three edge sets with distinct generation mechanisms: (1) identity-admiration chains (3,334 edges) where a person explicitly expresses admiration, self-comparison, or intellectual projection; (2) occupational citation edges (327) built from OpenAlex as an external blind data source (215 of 344 MGP nodes matched; 45,282 cited works); (3) institutionally assigned supervisor edges (172). Degree-preserving configuration models (50,000 rewirings) yield z = +10.78 (r=.193) for identity edges, z = -0.84 for citation edges and z = +0.47 (p=.77) for mentorship edges; the identity-vs-allocated contrast is about 11.6 SE. A preliminary apparent positive result (z=2.83) collapsed to 0.47 after 74 default-template cards were independently blind-coded and removed, and a common-method negative control (all-citation) is null. The externally blind citation null rules out systematic same-source labeling contamination. Homophily is therefore specific to active identity and self-projection, not to occupational tool use or institutional allocation. All labels are most-plausible attributions from public records, not diagnoses.