{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.twin","code":"thing-q159979","url":"https://ver.cy/models/thing/q159979/","name":"twin","alternateNames":["identical twin","fraternal twin","parasitic twin","twinless twin","vestigial twin"],"kind":"thing","status":"published","version":"0.2.0-wave.2","language":"en","classifiers":{"family":"Thing Registry","category":"Activities and processes","entryKind":"thing","plane":"ACT","domain":["ACT.PRC"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"One of two offspring produced in the same pregnancy, either identical twins from a single fertilised egg that splits or fraternal twins from two separate eggs, with rarer forms such as conjoined, parasitic and vanishing twins; twins are studied in genetics and psychology, raise particular questions in pregnancy care and family life, and feature widely in culture.","purpose":"Let an agent explain types of twins and how they arise, describe twin pregnancy care in general terms, support families of twins, and describe twin research and cultural significance.","scope":{"in":[],"out":[],"boundaries":[]},"distinguishingFeatures":["Multiple birth of two","Monozygotic or dizygotic","Shared or separate placentas","Special care needs"],"structure":{"bundles":[{"id":"types","name":"Types","description":"Kinds of twins.","layers":[{"id":"kinds","name":"Kinds","description":"Identical and fraternal.","findings":[{"id":"kinds-finding","name":"Kinds","description":"Kinds.","questions":[{"text":"How do identical and fraternal twins arise, and what determines whether they share a placenta?","kind":"definition"},{"text":"What are conjoined, parasitic and vanishing twins?","kind":"definition"}]}]},{"id":"zygosity","name":"Zygosity","description":"Determining zygosity.","findings":[{"id":"zygosity-finding","name":"Zygosity","description":"Zygosity.","questions":[{"text":"How is zygosity determined, and why can it be unclear at birth?","kind":"provenance"},{"text":"Can identical twins differ genetically?","kind":"provenance"}]}]}]},{"id":"pregnancy","name":"Pregnancy","description":"Twin pregnancy and birth.","layers":[{"id":"care","name":"Care","description":"Antenatal care.","findings":[{"id":"care-finding","name":"Care","description":"Antenatal care.","questions":[{"text":"How is a twin pregnancy monitored, and what risks are documented, according to guidelines?","kind":"provenance"},{"text":"Is the user seeking advice on their own pregnancy, which needs a clinician?","kind":"boundary"}]}]},{"id":"birth","name":"Birth","description":"Birth.","findings":[{"id":"birth-finding","name":"Birth","description":"Birth.","questions":[{"text":"What do guidelines say about timing and mode of twin birth?","kind":"provenance"},{"text":"Is there an emergency now?","kind":"boundary"}]}]}]},{"id":"family","name":"Family","description":"Raising twins.","layers":[{"id":"parenting","name":"Parenting","description":"Parenting twins.","findings":[{"id":"parenting-finding","name":"Parenting","description":"Parenting.","questions":[{"text":"What practical guidance and support exist for families with twins?","kind":"provenance"},{"text":"Which organisations help?","kind":"provenance"}]}]},{"id":"identity","name":"Identity","description":"Twin identity.","findings":[{"id":"identity-finding","name":"Identity","description":"Identity.","questions":[{"text":"How can twins be supported as individuals, according to psychologists and twins themselves?","kind":"provenance"},{"text":"What support exists for twinless twins?","kind":"provenance"}]}]}]},{"id":"science","name":"Science","description":"Twin studies and culture.","layers":[{"id":"studies","name":"Studies","description":"Twin studies.","findings":[{"id":"studies-finding","name":"Studies","description":"Twin studies.","questions":[{"text":"How are twin studies used to estimate heritability, and what are their limits?","kind":"provenance"},{"text":"Which registries exist?","kind":"provenance"}]}]},{"id":"culture","name":"Culture","description":"Twins in culture.","findings":[{"id":"culture-finding","name":"Culture","description":"Culture.","questions":[{"text":"How are twins treated in mythology, culture and different societies?","kind":"provenance"},{"text":"How common are twin births, according to statistics?","kind":"provenance"}]}]}]}]},"agentConduct":{"may":["Explain how identical and fraternal twins arise, citing medical and genetic sources.","Respect the individuality of each twin when describing them."],"mustNot":["Advise on the medical care of a twin pregnancy or birth for a specific person.","Assume identical twins are the same person in behaviour, records or identity checks.","Use one twin's genetic or medical data to make claims about the other without consent.","Present conjoined or parasitic twins as spectacle."],"requiresHuman":["Medical decisions in twin pregnancies or the separation of conjoined twins.","Using twins in research."]},"ethics":{"considerations":["Twins are individuals, yet are often compared and treated as a pair.","Shared DNA means one twin's genetic test reveals information about the other."],"affectedParties":["Twins","Parents during pregnancy","Research participants"]},"owners":{"steward":"Each twin is their own person; parents or guardians decide for children.","roles":[],"masterSystems":["Civil birth registers"]},"relations":[{"target":"Q25671","type":"parent","note":"registry parent class"},{"target":"multiple birth","type":"related","note":"category"},{"target":"sibling","type":"related","note":"family relation"},{"target":"pregnancy","type":"related","note":"context"},{"target":"genetics","type":"related","note":"twin studies"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.twin","Wikidata: Q159979 (https://www.wikidata.org/wiki/Q159979)"]},"properties":{"applicability":"not-applicable","items":[]},"recognition":{"applicability":"optional","items":["Same pregnancy","Identical or fraternal","Triplets and higher are other multiple births","Two siblings born of the same pregnancy, similar in appearance if identical."]},"capabilities":{"applicability":"required","items":["explain identical and fraternal twins","describe twin pregnancy and birth in general terms","support families and twins themselves","explain twin studies"]},"hazards":{"applicability":"required","items":["Complications of twin pregnancy","Assumptions about identical twins being the same","Agents giving medical advice"]},"interfaces":{"applicability":"required","items":["Clinical guidelines on multiple pregnancy","Birth registration rules","Research ethics for twin studies"]},"context":{"applicability":"required","items":["Two children from one pregnancy.","identical (monozygotic) twins","fraternal (dizygotic) twins","conjoined twins","parasitic and vestigial twins","twinless twins after loss"]}},"sources":[{"title":"Wikidata item Q159979: twin","url":"https://www.wikidata.org/wiki/Q159979","note":"identity and sense of the item"},{"title":"Wikipedia: Twin","url":"https://en.wikipedia.org/wiki/Twin","note":"general description of the item"}],"openQuestions":["Should conjoined twins be a separate entry?","How should clinical guidelines be linked?","How should twin organisations be localised?"],"resources":{"spec":"/models/things/publications/thing-q159979/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q159979/spec.json"],"providers":["Claude"],"researchStatus":"unreviewed","generatedAt":"2026-09-11T21:25:36Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"not-applicable","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-06T19:51:54+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass","interaction.properties":"Plane ACT: no invented physical properties."},"score":1.0}}