Talk:Twin/Archive 2

monozygotic/dizygotic
As far as I understand, monozygotic twins can never be of different sex (disregarding strange stuff that may happen during embryonal development which would be outside the scope of this article). If this is correct, it should be mentioned in the article. --BjKa (talk) 12:35, 26 March 2018 (UTC)

Regarding section "Types of twins and zygosity"
Comments from an interested reader who is not an authority. Wondering if this table would work better as a tree, or key. Types parasitic twin, vanishing twin, and conjoined twin seem to be on a spectrum having the same root condition, for example. Mvsmith (talk) 22:41, 21 January 2018 (UTC)
 * The text before the table should clarify that twins can occur in two main ways (monozygotically, polyzygotically) that have several subcategories depending on what happens during development.
 * The table needs a lot of work:
 * What does "x" signify? Presence of something, absence, not applicable, not done yet?
 * Column Zygocity has no entries although of central import.
 * Column Occurrence has only one entry, but would serve to indicate relative importance of each type of twinning in column Common name. Types polar body and half-identical are apparently only theoretical.
 * Column Identification has no entries. Identification by morphology, genetic testing, developmental events?
 * Similarly, empty rows...


 * I agree on all points. Also, the term "chromosome profile" is used but never defined, and it occurs nowhere else in Wikipedia. --Thnidu (talk) 08:22, 15 January 2019 (UTC)

This article needs editing for clarification
Thanks to the editors who composed this informative article. But IMHO, a good deal of it is rather obtuse. Perhaps some knowledgeable person could render the article more understandable. (PeacePeace (talk) 22:43, 28 May 2018 (UTC)) Just changed the order of the names on the kellys picture — Preceding unsigned comment added by 190.195.19.49 (talk) 06:23, 1 June 2019 (UTC)

ethnicity section
"10% twin birts rate in Linha Sao Pedro" (source No:49. https://www.cambridge.org/core/journals/amg-acta-geneticae-medicae-et-gemellologiae-twin-research/article/study-on-possible-increase-in-twinning-rate-at-a-small-village-in-south-brazil/C2D3948053CCEA4E79AAA0A4C5B10457) the abstract available for browsing says two things that make this source somewhat questionable from the point of statistical validity: the study is based on a small population settlement for a period of 1990-1994(low sample size means that the normal random fluctuation of rates eg that is like base a study of football on watching only one player of a football team during four minutes of the game and then conclude that because during this study period the one player scored a goal the average of the team is every member scores one goal every 4 minutes). see more about low samples more prone to extreme proportion counts (eg. even one case has a much higher effect on the small populations calculated occurance rate than in a city of much more populations) in daniel kahneman: thinking fast and slow (terrible book, but makes some good points about the relation between statistics and reasoning fallacies - it has a WP article you can look up).

apart from the small sample size and short period of time the arguments of the cited source (abstract) seem to be sound but the methodology is flawed because of the above. im not telling you to remove the source but you should either consider it, or add a warning to the article text about the cited study's small scope making any conclusions derived from it not fully trustable.

the study authors could have studied one single couple having one singleton and then a twin pregnancy and say they are studying the extremely high 50% twin rate in the population of two persons. 89.134.199.32 (talk) 22:40, 18 July 2019 (UTC).

Change to this?
Fraternal twins can be any of the following:

Female–female: Sometimes called sororal twins (25%). Male–male twins: Rarely called leviral twins (25%). Male–female twins: This is the most common pairing (50%), simply by virtue of it encompassing both "male-female" (25%) and "female-male" (25%) twins.

I'm sorry I had to coin a term but I put it on the talk page to compensate. — Preceding unsigned comment added by LukeyBear11 (talk • contribs) 03:45, 18 November 2019 (UTC)

Photo: Fraternal twins
Changed photo - the is a cute photo, but the babies look as much identical as fraternal (please don't tell me they must be different genders due to the colours of the clothes).Davidships (talk) 18:26, 16 February 2020 (UTC)

Suggestion for improvement
This article is sorely lacking in content post-birth of twins. Here is an entire book on the subject. Calliopejen1 (talk) 08:24, 25 July 2020 (UTC)

When cousins are two of a kind
No mention of identical first cousins (dispersed between continents)? They laugh alike; they walk alike; at times they even talk alike. TheScotch (talk) 15:07, 29 September 2021 (UTC)

HI

Image pertinence
I have replaced the image of the Olsen twins with that of child-age fraternal, look-alike twin sisters, as the latter fulfills the variety criterion of MOS:PERTINENCE. With that provided, the further addition of the Olsen twins image, apart from the visual-to-text ratio being at its utmost, would simply be superfluous as instanced in the MOS and will not be adding to anything provided in the article whether it be in text or illustration. QuestFour (talk) 17:54, 17 October 2021 (UTC)
 * The variety is fulfilled by the illustration of the exception - that fraternal twins look alike to a degree to be used interchangeably, even well beyond baby age. Two images portraying two different special cases, that'*s as illustration should be. While I agree that the fraternal twin babies you've added look very similar and can hardly be distinguished from each other - and from identical twins -, babies in general look more similar to each other than adults so, and the image overall does not serve well as an illustration. --KnightMove (talk) 11:33, 18 October 2021 (UTC)
 * The MOS presents the variety gauge in the form mentioned above and instructs to "depict a variety of ages, genders, and ethnicities"; the point regarding age and similarity in looks in twins is solely impressionistic and is not representative of what is provided in the article. As can be shown in the article's revision history, various image of twin actors, actresses and celebrities, including the Olsens, have been added to the article throughout its lifespan but subsequently removed due to similar circumstances. Therefore, the current image does satisfy all of the conditions stated in the MOS. QuestFour (talk) 18:39, 18 October 2021 (UTC)
 * The rule you quote is certainly not to be understood as "all persons on different images included must be different in age, gender, AND ethnicity each." In this case, your image of the babies napping would also be against the rule, as the babies apparently have the same ethnicity and nationality as the Kelly brothers. The Olsen twins differ in gender and heavily in age from the Kelly brothers, which would certainly suffice... if it even were necessary.
 * The rule is to be read in context of the general guideline "Images must be significant and relevant in the topic's context, not primarily decorative. They are often an important illustrative aid to understanding." This exactly is fulfilled with adding look-alike fraternal twins, not to make the reader to superficially conclude "identical twins look alike, fraternal twins don't". So your implicit assumption I would add the image just as a decoration with just another famous twin couple is not correct.
 * I will call WP:Third opinion. --KnightMove (talk) 08:27, 19 October 2021 (UTC)
 * I have inserted an image of Lisa-Kaindé and Naomi Diaz of the duo Ibeyi, along with a similar caption to what was inserted prior. The image fulfills the conditions stated in the MOS and above and has the twins in a front-facing position. It is also a high quality portrait akin to the images provided in the article. QuestFour (talk) 08:50, 19 October 2021 (UTC)
 * As no third opinion is coming in, so be it, I accept this as a compromise. --KnightMove (talk) 05:59, 22 October 2021 (UTC)

Do identical twins have identical wisdom teeth?
This question is a little outside my bailiwick, and as far as I can tell, the answer isn't anywhere on Wikipedia. I poked around Google Scholar a bit, but what I found didn't answer the question directly. If anyone knows the answer / has a good source relating to this, please let me know and/or add it to this article, or perhaps the Wisdom teeth article, or perhaps both. Thanks in advance for any help! Joe (talk) 03:06, 13 February 2022 (UTC)

Terminology for individuals
Regarding this passage from the opening of the article: "In contrast, a fetus that develops alone in the womb (the much more common case, in humans) is called a singleton, and the general term for one offspring of a multiple birth is a multiple. Unrelated look-alikes whose resemblance parallels that of twins are referred to as doppelgängers."


 * Singleton: there was one post to talk years back that brought into question use of this term. However, it appears in the scientific literature, such as in, a clinical paper that has in the Abstract (Study design section) "...data on all women with singleton and twin gestations complicated by PROM...."  This type of usage suggests the use of "singleton" for a child of a singleton pregnancy, just like below for "twin" for a child of a twin pregnancy.
 * Multiple: I've been trying to find use of this term. The more common approach than using "multiple" is to refer using a derivative of the common multiplicity term.  So, in the case of twins, an individual is referred to as a "twin" (Dorlands, 28th edition 2009, pg. 877), "triplet" for a triplet birth (pg. 869), "quadruplet" for one person from a quadruple pregnancy (pg. 705), "quintuplet" (pg. 705), "sextuplet" (pg. 758), "septuplet" (pg. 756) & mdash; which is as far as the dictionary goes.  The text has terms for multiple pregnancies (multigravida and multipara), but these terms refer to multiple different pregnancies and not to a multi-birth pregnancy.  Also, the current citation to a MedLinePlus article only alludes to the use of the term multiple and doesn't actually define it.
 * Dopplegangers: the supporting citation related to a "generalized user modeling system" which has this name. I would suggest dropping this particular sentence altogether.

I can do the rewrite and re-citationing of the passage, but wanted to see if the concept passed muster here first. --User:Ceyockey ( talk to me ) 23:05, 7 April 2022 (UTC)

Twinning across the Developing World needs correction n. America appears twice
I'm probably doing this wrong but I found an error in the above-titled section. North America appears in both the 6-9 and 9-12 per thousand rate lists; I'm assuming one of the two is actually S. America, but time does not permit my investigating it and I didn't want to forget. please ignore this if it's out of line. Thanks! frannie (talk) 18:56, 27 August 2022 (UTC)

Polar body twins (hypothetical)
The Polar body article says that "Polar body twinning is a hypothesized form of twinning in meiosis, where one or more polar bodies do not disintegrate and are fertilized by sperm". This article has one source supposedly documenting one occurrence in humans. So what's the deal? One occurrence is pretty weak evidence. -- Valjean (talk) ( PING me ) 19:22, 20 December 2023 (UTC)

For the Citation Needed under 'Bi-paternal twins'
I have reason to believe that for the citation needed under 'Bi-paternal twins', this article https://pubmed.ncbi.nlm.nih.gov/1488855/ may be the missing citation. I'm unsure if that link is suitable, as it contains the abstract of the study.

ValiantEar564 (talk) 05:24, 5 March 2024 (UTC)