Twin
one of two offspring produced in the same pregnancy
Twins are two offspring produced by the same pregnancy. Twins can be either monozygotic ('identical'), meaning that they develop from one zygote, which splits and forms two embryos, or dizygotic ('non-identical' or 'fraternal'), meaning that each twin develops from a separate egg and each egg is fertilized by its own sperm cell. Since identical twins develop from one zygote, they will share the same chromosomal sex, while fraternal twins may or may not. In very rare cases, fraternal or (semi-) identical twins can have the same mother and different fathers.
In contrast, a fetus that develops alone in the womb (the much more common case in humans) is a singleton; one of a multiple birth is a multiple. Unrelated look-alikes whose resemblance parallels that of twins are referred to as doppelgänger.
Statistics
The human twin birth rate in the United States rose 76% from 1980 through 2009, from 9.4 to 16.7 twin sets (18.8 to 33.3 twins) per 1,000 births. The Yoruba people have the highest rate of twinning in the world, at 45–50 twin sets (90–100 twins) per 1,000 live births, possibly because of high consumption of a specific type of yam containing a natural phytoestrogen which may stimulate the ovaries to release an egg from each side. In Central Africa, there are 18–30 twin sets (or 36–60 twins) per 1,000 live births. In South America, South Asia, and Southeast Asia, the lowest rates are found: only six to nine twin sets per thousand live births.
“Twin” enters the record as one of two offspring produced in the same pregnancy. Crown Archives preserves that source wording while asking what Twin, offspring and produced can confirm, complicate or overturn.
Why this record matters
“Twin” is worth following because a concise public description often conceals a longer documentary argument. Here, Twin, offspring and produced provides the most credible route into that argument.
Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Sep 9, 2026. The linked authority identifier is Q159979. The Library of Congress control number is sh85139043. None of the 1 selected statements returned an explicit reference. The first chronological checks are 1980 and 2009.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Twin”, its source revision and the description used here.
- Expand the search: follow Twin primary sources, Twin archive and Twin research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Twin”?
- Which cited source is closest to the event, object or claim?
- Which institution is responsible for the underlying evidence?
Search terms from this dossier
This entry incorporates text from “Twin” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.