• Genes
  • Twins are a valuable source for observation because they allow the study of environmental influence and varying genetic makeup: "identical" or monozygotic (MZ) twins share nearly 100% of their genes, which means that most differences between the twins (such as height, susceptibility to boredom, intelligence, depression, etc.) are due to experiences that one twin has but not the other twin. (wikipedia.org)
  • Modern twin studies have shown that almost all traits are in part influenced by genetic differences, with some characteristics showing a stronger influence (e.g. height), others an intermediate level (e.g. personality traits) and some more complex heritabilities, with evidence for different genes affecting different aspects of the trait - as in the case of autism. (wikipedia.org)
  • More recent study is from Sir Francis Galton's pioneering use of twins to study the role of genes and environment on human development and behavior. (wikipedia.org)
  • pregnancies
  • Besides the capability to assess chromosomal aneuploidy, the ability to measure the fetal DNA contributions of individual fetuses of dizygotic twins could serve as a useful internal positive control for any tests based on analyzing circulating fetal DNA in maternal plasma for these pregnancies, such as noninvasive fetal RHD genotyping (26) and single-gene disease diagnosis (13, 27, 28). (thefreedictionary.com)
  • METHODS
  • Using the proposed methods as an alternative and major extension to the classical twin models, our analyses with a large-scale Finnish twin data set (19,510 MZ twins and 27,312 DZ same-sex twins) discover that the variances of the A, C, and E components for body mass index (BMI) change substantially across life span in different patterns and the heritability of BMI drops to ∼50% after middle age. (genetics.org)
  • Estimation methods and software such as structural equation modeling (SEM) based on the classical twin models consisting of additive genetic, common, and unshared environmental effects have been well established and extensively adopted ( Rijsdijk and Sham 2002 ). (genetics.org)
  • however
  • However, the time it takes for an egg to split into twins after fertilization does affect the similarities between the children. (bellaonline.com)
  • However, heritability estimation based on the classical twin models does not take into account dynamic behavior of the variance components over age. (genetics.org)
  • However, dizygotic twins may also look very different from each other. (wikipedia.org)
  • rates
  • Trends in twin neonatal mortality rates in the United States, 1989 through 1999: influence of birth registration and obstetric intervention. (semanticscholar.org)
  • behavior
  • By comparing many hundreds of families with twins, researchers can then understand more about the roles of genetic effects, shared environment, and unique environment in shaping behavior. (wikipedia.org)
  • biology
  • Twin research is considered a key tool in behavioral genetics and in content fields, from biology to psychology. (wikipedia.org)
  • common
  • RESULTS: There was some evidence for association between DZ twinning and a common intronic BMP15 variant (rs3897937), but this was not significant after correction for multiple testing. (edu.au)
  • This is the most common type of twin. (wikipedia.org)
  • similar
  • Twins have been of interest to scholars since early civilization, including the early physician Hippocrates (5th century BCE), who attributed similar diseases in twins to shared material circumstances,[citation needed] and the stoic philosopher Posidonius (1st century BCE), who attributed such similarities to shared astrological circumstances. (wikipedia.org)
  • The monozygotic twins also chose spouses and best friends who were more similar to their co-twins' friends and spouses than did dizygotic twins. (wikipedia.org)
  • Neither result was seen to a similar degree in dizygotic twins, offering strong favour for high genetic aetiology. (wikipedia.org)
  • case
  • Although there are few case reports of Brown syndrome in twins, combination of these reports may elucidate the genetic basis of this disease. (biomedcentral.com)
  • Also there are few case reports of Brown syndrome in twins that might be indicative of a possible autosomal dominant or recessive inheritance. (biomedcentral.com)
  • Full
  • I gained 25-30 lbs with my singleton and she was 8 lbs 11 oz so I'm hoping that since I've already gained 30 lbs the twins will be at least 6 lbs each at full term. (mothering.com)
  • Environment
  • Twins also share many aspects of their environment (e.g., uterine environment, parenting style, education, wealth, culture, community) because they are born into the same family. (wikipedia.org)
  • Twins are also useful in showing the importance of the unique environment (specific to one twin or the other) when studying trait presentation. (wikipedia.org)