Nevertheless, twin designs and methods are extremely useful for understanding the extent to which psychological and medical disorders, as well as behaviors and traits, are influenced by genetic factors. This information can then be used to develop better ways to prevent and treat disorders and maladaptive behaviors.

(Psychology) Which observation did researchers make in studies on separated twins? A. Separated twins develop traits that differ according to the environments in which they are raised.

Modern twin studies have concluded 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 …

Many of those scientists had previously conducted twin studies. As the researchers mention in their article, they studied monozygotic twins who were separated early in life and raised apart, because they provided a way to separate the influence of environmental and genetic factors on human characteristics.

It is clear that the twin method is no more able to disentangle the potential roles of genetic and environmental influences on behavioral traits and disorders than is the finding from family studies that such traits and disorders tend to “run in the family.” Given that both research methods are confounded by …

The most common objections to twin studies have been: (1) Twins have almost always been reared to- gether and this common rearing may have con- tributed to increased concordance in monozygotic (MZ) twins because of psychological characteris- tics unique to such pairs (8, 29);

Which situation is most consistent with the results of twin studies of schizophrenia? The correct answer was: b. Schizophrenia is more likely to materialize in a twin who experiences extreme stress..

Epigenetics most often involves changes that affect gene activity and expression, but the term can also be used to describe any heritable phenotypic change. Such effects on cellular and physiological phenotypic traits may result from external or environmental factors, or be part of normal development.

[2] Analyzing classic studies of the genetics of schizophrenia done as early as in 1930s, Fischer concludes that a concordance rate for psychosis of about 50% in monozygotic twins seems to be a realistic estimate, which is significantly higher than that in dizygotic twins of about 10–19%.

Genain quadruplets (born in 1930) are a set of identical quadruplet girls notable for all being schizophrenic, demonstrating a large genetic component to the cause of the disease.

Huntington disease affects an estimated 3 to 7 per 100,000 people of European ancestry. The disorder appears to be less common in some other populations, including people of Japanese, Chinese, and African descent.

Overall, genetics has more influence than parents do on shaping our personality. Molecular genetics is the study of which genes are associated with which personality traits. The largely unknown environmental influences, known as the nonshared environmental effects, have the largest impact on personality.

Identical triplets or quadruplets are very rare and result when the original fertilized egg splits and then one of the resultant cells splits again (for triplets) or, even more rarely, a further split occurs (for quadruplets). The odds of having identical triplets is unclear.

Once an extremely rare phenomenon, fertility treatments have made multiple births slightly more common today. But conceiving sextuplets without the use of fertility treatments is extremely rare. In fact, the odds of giving birth to sextuplets spontaneously are one in 4.7 billion.

Although it’s entirely possible to have a mix of identical and fraternal siblings in a single set of multiples (just look at the Busby quints; Ava and Olivia are identical, while the rest of the girls are fraternal), all of the Waldrop sextuplets are fraternal, People reported.

Sweet Home Sextuplets mom Courtney Waldrop did have some fertility issues. But, Courtney and Eric Waldrop knew they wanted a big family with at least four children. Then, Courtney Waldrop got pregnant with the twins. After that, the Waldrop couple decided they still wanted one more child to complete their family.

A Simple Chart of Multiple Birth Terms

Fraternal twins are also dizygotic twins. They result from the fertilization of two separate eggs during the same pregnancy. Fraternal twins may be of the same or different sexes.

The current holder of the Guinness record is American Nadya Suleman, who gave birth to eight premature but otherwise healthy children in 2009.