Synaesthesia: Discordant<i>male</i>monozygotic twins
Bibliographic record
Abstract
Grapheme-color synaesthesia, a condition in which achromatic graphemes elicit vivid experiences of color is believed to be a genetically determined trait. We describe a study of 10-year-old twin brothers who are physically identical in appearance but who have considerably different conscious experiences. A phenotypic analysis that measured the consistency of grapheme-color pairings over test-retest confirmed that one twin has grapheme-color synaesthesia and the other twin does not. A genotypic analysis using sixteen microsatellite loci confirmed that the twins are monozygotic. These findings are problematic for previous suggestions that synaesthesia is an X-linked dominant trait. At the very least, the findings show that the penetrance of the genotype for synaesthesia is incomplete and that any view suggesting that synaesthesia is simply an X-linked dominant trait is therefore also incomplete and possibly even incorrect. The findings also negate a previous suggestion, based on a study of female monozygotic twins, that discordance of synaesthesia in identical twins is due to X-inactivation. In general, the findings raise serious questions regarding whether it is possible at this time to establish the genetic contribution to synaesthesia.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".