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Twins
Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of Twin Last Editorial Review: 19 June 2000 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 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 ( heteropaternal superfecundation). 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 doppelgänger. Statistics The human twin birth rat ...
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Multiple Birth
A multiple birth is the culmination of a multiple pregnancy, wherein the mother gives birth to two or more babies. A term most applicable to vertebrate species, multiple births occur in most kinds of mammals, with varying frequencies. Such births are often named according to the number of offspring, as in ''twins'' and ''triplets''. In non-humans, the whole group may also be referred to as a ''litter'', and multiple births may be more common than single births. Multiple births in humans are the exception and can be exceptionally rare in the largest mammals. A multiple pregnancy may be the result of the fertilization of a single egg that then splits to create identical fetuses, or it may be the result of the fertilization of multiple eggs that create fraternal ("non-identical") fetuses, or it may be a combination of these factors. A multiple pregnancy from a single zygote is called '' monozygotic'', from two zygotes is called '' dizygotic'', or from three or more zygotes is called ...
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Superfecundation
Superfecundation is the fertilization of two or more ova from the same menstrual cycle by sperm from the same or different males, whether through separate acts of intercourse or during a single sexual encounter with multiple males (e.g. double penetration). This can potentially result in twin babies that have different biological fathers. The term superfecundation is derived from fecund, meaning able to produce offspring. Homopaternal superfecundation is a form of twinning where fertilization of two separate ova occurs as a result of two or more distinct instances of intercourse or insemination with the same male partner or donor, leading to fraternal twins. Heteropaternal superfecundation, on the other hand, is an atypical form of twinning that results in twins that are genetically half siblings – sharing the same biological mother, but with different biological fathers. Conception Sperm cells can live inside a human female's body for up to five days, and once ovulation occu ...
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Sibling
A sibling is a relative that shares at least one parent with the other person. A male sibling is a brother, and a female sibling is a sister. A person with no siblings is an only child. While some circumstances can cause siblings to be raised separately (such as foster care or adoption), most societies have siblings grow up together. This causes the development of strong emotional bonds, with siblinghood considered a unique type of relationship. The emotional bond between siblings is often complicated and is influenced by factors such as parental treatment, birth order, personality, and personal experiences outside the family. Medically, a full-sibling is a first-degree relative and a half-sibling is a second-degree relative as they are related by 50% and 25%, respectively. Definitions The word ''sibling'' was reintroduced in 1903 in an article in '' Biometrika'', as a translation for the German ''Geschwister'', having not been used since Middle English, specifically 142 ...
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Yoruba People
The Yoruba people ( ; , , ) are a West African ethnic group who inhabit parts of Nigeria, Benin, and Togo, which are collectively referred to as Yorubaland. The Yoruba constitute more than 50 million people in Africa, are over a million outside the continent, and bear further representation among the African diaspora. The vast majority of Yoruba are within Nigeria, where they make up 20.7% of the country's population according to Ethnologue estimations, making them one of the largest List of ethnic groups of Africa, ethnic groups in Africa. Most Yoruba people speak the Yoruba language, which is the Niger–Congo languages, Niger-Congo language with the largest number of native or L1 speakers. Geography In Africa, the Yoruba culture, Yoruba are contiguous with the Yoruboid languages, Yoruboid Itsekiri to the south-east in the northwest Niger Delta, Bariba people, Bariba to the northwest in Benin and Nigeria, the Nupe people, Nupe to the north, and the Ebira to the northeast in ...
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Zygosity
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same locus (genetics), loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal Sex-determination system#Chromosomal determination, sex-determination system. If both alleles of a diploid organism are the same, the organism is #Homozygous, homozygous at that locus. If they are different, the organism is #Heterozygous, heterozygous at that locus. If one allele is missing, it is #Hemizygous, hemizygous, and, if both alleles are missing, it is #Nullizygous, nullizygous. The ...
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Look-alike
A look-alike, or double, is a person who bears a strong physical resemblance to another person, excluding cases like twins and other instances of Family resemblance (anthropology), family resemblance. Some look-alikes have been notable individuals in their own right. Other notable look-alikes have been notable solely for resembling well-known individuals, such as M. E. Clifton James, Clifton James, who acted as a double for British Field Marshal Bernard Montgomery during World War II. Some look-alikes who have resembled celebrity, celebrities have worked as entertainers, impersonating them on stage (theatre), stage or screen, or at venues like party, parties and corporate entertainment, corporate functions. Professional look-alikes have often been represented by talent agency, talent agencies specializing in celebrity impersonators. Close physical resemblance between individuals is also a common plot point in works of fiction. Research According to a paper published in 2022 ...
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Mauch Twins
William John Mauch (July 6, 1921 – September 29, 2006) and his identical twin brother, Robert Joseph Mauch (July 6, 1921 – October 15, 2007), were child actors in the 1930s. They had starring roles in the 1937 film ''The Prince and the Pauper (1937 film), The Prince and the Pauper'', based on the The Prince and the Pauper, 1881 novel of the same name by Mark Twain. Early life Billy and Bobby were born in Peoria, Illinois, Peoria, Illinois, to Felix, an employee of the Toledo, Peoria & Western Railroad and Marguerite Mauch, née Burley. Billy was older than Bobby by ten minutes. They began singing and acting in radio at the age of seven and later appeared in print advertisements before signing a contract with Warner Bros. Career After moving with their mother to Hollywood in 1935, Billy was cast as the young title character in the film ''Anthony Adverse'' because he resembled Fredric March, who was to play Adverse as an adult. His brother Bobby was his stand-in for t ...
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Ovulation
Ovulation is an important part of the menstrual cycle in female vertebrates where the egg cells are released from the ovaries as part of the ovarian cycle. In female humans ovulation typically occurs near the midpoint in the menstrual cycle and after the follicular phase. Ovulation is stimulated by an increase in luteinizing hormone (LH). The ovarian follicles rupture and release the secondary oocyte ovarian cells. After ovulation, during the luteal phase, the egg will be available to be fertilized by sperm. If it is not, it will break down in less than a day. Meanwhile, the uterine lining ( endometrium) continues to thicken to be able to receive a fertilized egg. If no conception occurs, the uterine lining will eventually break down and be shed from the body via the vagina during menstruation. Some people choose to track ovulation in order to improve or aid becoming pregnant by timing intercourse with their ovulation. The signs of ovulation may include cervical muc ...
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Doppelgänger
A doppelgänger ( ), sometimes spelled doppelgaenger or doppelganger, is a ghostly double of a living person, especially one that haunts its own fleshly counterpart. In fiction and mythology, a doppelgänger is often portrayed as a ghostly or paranormal phenomenon and usually seen as a harbinger of bad luck. Other traditions and stories equate a doppelgänger with an evil twin. In modern times, the term twin stranger is occasionally used. Spelling The word "doppelgänger" is a loanword from the German noun , literally meaning "double-walker". The singular and plural forms are the same in German, but English writers usually prefer the plural "doppelgängers". In German, there is also a feminine form, (plural ). The first-known use, in the form , occurs in the novel '' Siebenkäs'' (1796) by Jean Paul, in which he explains his newly coined word in a footnote; the word also appears in the novel, but with a different meaning. In German, the word is written (as is usual with Ge ...
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Red-haired Siblings
Red hair, also known as ginger hair, is a human hair color found in 2–6% of people of Northern or Northwestern European ancestry and lesser frequency in other populations. It is most common in individuals homozygous for a recessive allele on chromosome 16 that produces an altered version of the MC1R protein. Red hair varies in hue from a deep burgundy or bright copper, or auburn, to burnt orange or red-orange to strawberry blond. Characterized by high levels of the reddish pigment pheomelanin and relatively low levels of the dark pigment eumelanin, it is typically associated with fair skin color, lighter eye color, freckles, and sensitivity to ultraviolet light. Cultural reactions to red hair have been varied. The term "redhead" has been in use since at least 1510, while the term "ginger" is sometimes used, especially in Britain and Ireland, to describe a person with red hair. The origin of red hair can be traced to Central Asia, caused by a mutation in the MC ...
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Uterus
The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, fetal development of one or more Fertilized egg, fertilized eggs until birth. The uterus is a hormone-responsive sex organ that contains uterine gland, glands in its endometrium, lining that secrete uterine milk for embryonic nourishment. (The term ''uterus'' is also applied to analogous structures in some non-mammalian animals.) In humans, the lower end of the uterus is a narrow part known as the Uterine isthmus, isthmus that connects to the cervix, the anterior gateway leading to the vagina. The upper end, the body of the uterus, is connected to the fallopian tubes at the uterine horns; the rounded part, the fundus, is above the openings to the fallopian tubes. The connection of the uterine cavity with a fallopian tube is called the utero ...
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Spermatozoon
A spermatozoon (; also spelled spermatozoön; : spermatozoa; ) is a motile sperm cell (biology), cell produced by male animals relying on internal fertilization. A spermatozoon is a moving form of the ploidy, haploid cell (biology), cell that is the male gamete that Fertilization, joins with an ovum to form a zygote. (A zygote is a single cell, with a complete set of chromosomes, that normally develops into an embryo.) Sperm cells contribute approximately half of the nuclear gene, genetic information to the diploid offspring (excluding, in most cases, mitochondrial DNA). In mammals, the sex of the offspring is determined by the sperm cell: a spermatozoon bearing an X chromosome will lead to a female (XX) offspring, while one bearing a Y chromosome will lead to a male (XY) offspring. Sperm cells were first observed in Antonie van Leeuwenhoek's laboratory in 1677. Mammalian spermatozoa Humans The sperm cell of ''Homo sapiens'' is the small Gamete, reproductive cell produced by m ...
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