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Twins And Handedness
Handedness, Left-handedness always occurs at a lower frequency than right-handedness. Generally, left-handedness is found in 10.6% of the overall population. Some studies have reported that left-handedness is more common in twins than in twin, singletons, occurring in 21% of people who are twins. However other studies did not find a higher left-handedness prevalence in twins compared to singletons. Twins and Singletons Left Hand Prevalence Twin, Monozygotic twins also known as identical twins are siblings that share the same genetic information because of their prenatal development. Monozygotic twins result from the fertilization of one egg and the division of that single embryo forming two embryos. However, just because a set of twins share the same genetic information, it does not mean they will exhibit the same traits and behaviors. There are different versions of a gene, which are callealleles How a gene is expressed depends on the development of an individual throughout their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Handedness
In human biology, handedness is an individual's preferential use of one hand, known as the dominant hand, due to it being stronger, faster or more Fine motor skill, dextrous. The other hand, comparatively often the weaker, less dextrous or simply less subjectively preferred, is called the non-dominant hand. In a study from 1975 on 7688 children in US grades 1-6, Left handers comprised 9.6% of the sample, with 10.5% of male children and 8.7% of female children being left-handed. Handedness is often defined by one's writing hand, as it is fairly common for people to prefer to do some tasks with each hand. There are examples of true ambidexterity (equal preference of either hand), but it is rare—most people prefer using one hand for most purposes. Most of the current research suggests that left-handedness has an epigenetic marker—a combination of genetics, biology and the environment. Because the vast majority of the population is right-handed, many devices are designed for u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Twin
Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast 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 rare cases 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 doppelgängers. Statistics The human twin birth rate in the United States rose 76% from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Twin
Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast 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 rare cases 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 doppelgängers. Statistics The human twin birth rate in the United States rose 76% from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerebellum
The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebellum plays an important role in motor control. It may also be involved in some cognition, cognitive functions such as attention and language as well as emotion, emotional control such as regulating fear and pleasure responses, but its movement-related functions are the most solidly established. The human cerebellum does not initiate movement, but contributes to Motor coordination, coordination, precision, and accurate timing: it receives input from sensory systems of the spinal cord and from other parts of the brain, and integrates these inputs to fine-tune motor activity. Cerebellar damage produces disorders in Fine motor skill, fine movement, Equilibrioception, equilibrium, Human positions, posture, and motor learning in humans. Anatomica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cross-dominant
Cross-dominance, also known as mixed-handedness, hand confusion, or mixed dominance, is a motor skill manifestation in which a person favors one hand for some tasks and the other hand for others, or a hand and the contralateral leg. For example, a cross-dominant person might write with the right hand and do everything else with the left one, or manage and kick a ball preferentially with the left leg. It can also refer to mixed laterality, which refers to a person favoring eyes, ears, feet, or hands on one side of the body. A person who is cross-dominant can also be stronger on the opposite side of the body that they favor; for example, a right-handed person can be stronger on the left side. Cross-dominance can often be a problem when shooting or in activities that require aim, although athletes can still achieve success in sports that require accuracy, like passing in American football and shooting in basketball. In baseball In baseball a left-handed batter is about two ste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Family History (medicine)
In medicine, a family history (FH or FHx) consists of information about disorders of direct blood relatives of the patient. Genealogy typically includes very little of the medical history of the family, but the medical history could be considered a specific subset of the total history of a family. Accurate knowledge of a patient's family history may identify a predisposition to developing certain illnesses, which can inform clinical decisions and allow effective management or even prevention of conditions. Eugenic Origins and Applications Early mentions of family medical histories in medical literature date from the 1840s. Henry Ancell mentioned inquiring about the family history of a patient in a medical case study in 1842, noting that the patient's presenting concern appears to be present in relatives and remarking on the prolific reproduction of her female relatives. In 1849, W.H. Walshe argued in a lecture at University College Hospital that in addition to a history of the pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birth
Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the fetus at a developmental stage when it is ready to feed and breathe. In some species the offspring is precocial and can move around almost immediately after birth but in others it is altricial and completely dependent on parenting. In marsupials, the fetus is born at a very immature stage after a short gestation and develops further in its mother's womb pouch. It is not only mammals that give birth. Some reptiles, amphibians, fish and invertebrates carry their developing young inside them. Some of these are ovoviviparous, with the eggs being hatched inside the mother's body, and others are viviparous, with the embryo developing inside her body, as in the case of mammals. Mammals Large mammals, such as primates, cattle, horses, some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gestational Age (obstetrics)
In obstetrics, gestational age is a measure of the age of a pregnancy which is taken from the beginning of the woman's last menstrual period (LMP), or the corresponding age of the gestation as estimated by a more accurate method if available. Such methods include adding 14 days to a known duration since fertilization (as is possible in in vitro fertilization), or by obstetric ultrasonography. The popularity of using this definition of gestational age is that menstrual periods are essentially always noticed, while there is usually a lack of a convenient way to discern when fertilization occurred. Gestational age is contrasted with fertilization age which takes the date of fertilization as the start date of gestation. The initiation of pregnancy for the calculation of gestational age can differ from definitions of initiation of pregnancy in context of the abortion debate or beginning of human personhood. Methods According to American College of Obstetricians and Gynecologists, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hair Whorl
A hair whorl is a patch of hair growing in a circular direction around a visible center point. Hair whorls occur in most hairy animals, on the body as well as on the head. Hair whorls, also known as crowns, swirls, or trichoglyphs, can be either clockwise or counterclockwise in direction of growth. In human theories Hair whorls on the head ( parietal whorls) have been studied by some behaviorists. Most people have clockwise scalp hair-whorls. Parietal whorls which are considered to be normal scalp patterns could be a single whorl or double whorls. Cases of triple parietal whorls are less common. Amar J. S. Klar conducted research to see if there was a genetic link between handedness and hair-whorl direction. He found that 8.4% of right-handed people and 45% of left-handed people have counterclockwise hair-whorls. His research suggested that a single gene may control both handedness and hair-whorl direction.Human handedness and scalp hair-whorl direction develop from a common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Social Pressure
Peer pressure is the direct or indirect influence on peers, i.e., members of social groups with similar interests, experiences, or social statuses. Members of a peer group are more likely to influence a person's beliefs, values, and behavior. A group or individual may be encouraged and want to follow their peers by changing their attitudes, values or behaviors to conform to those of the influencing group or individual. For the individual affected by peer pressure, this can have both a positive or negative influence on them. Social groups include both ''membership groups'' in which individuals hold "formal" membership (e.g. political parties, trade unions, schools) and cliques in which membership is less clearly defined. However, a person does not need to be a member or be seeking membership of a group to be affected by peer pressure. An individual can be in a crowd, a group of many cliques, and still be affected by peer pressure. Research suggests that organizations as well ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Footedness
Footedness is the natural preference of one's left or right foot for various purposes. It is the foot equivalent of handedness. While purposes vary, such as applying the greatest force in a certain foot to complete the action of kick as opposed to stomping, footedness is most commonly associated with the preference of a particular foot in the leading position while engaging in foot- or kicking-related sports, such as association football and kickboxing. A person may thus be left-footed, right-footed or ambipedal (able to use both feet equally well). Ball games In association football, the ball is predominantly struck by the foot. Footedness may refer to the foot a player uses to kick with the greatest force and skill. Most people are right-footed, kicking with the right leg. Capable left-footed footballers are rare and therefore quite sought after. As rare are "two-footed" players, who are equally capable with both feet. Such players make up only one sixth of players in the top prof ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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