Benefits and Dilemmas of Twin Studies

The current research talks about the benefits and dilemmas related to twin studies. It helps in understanding the genetic variability patterns. Additionally, it helps in understanding the effects of evolution better. However there are a number of dilemmas which further affects the pattern and correctness of the results produced.

Running head: TWIN STUDIES
Twin Studies
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Table of Contents
Introduction......................................................................................................................................1
Benefits of twin studies...................................................................................................................1
Ethical dilemmas related to twin studies.........................................................................................3
Conclusion.......................................................................................................................................4
References........................................................................................................................................5

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Introduction
The basic reason for twin studies is that it helps to know whether environment interact
with the genes and give rise to variation. Therefore, the following essay involves the evaluation
of benefits and dilemmas associated with twin studies for causes of variation.
Benefits of twin studies
Twin studies enable to make investigations into the environmental and genetic causes of
variation in context to multi-factorial diseases. The monozygotic twins (identical twins) (MZ)
have exactly same, identical genes. However, as they grow, there are striking developments of
subtle differences between the twins despite of the fact that they share same genes.
Although, MZ are similar, there is caveat to investigation of twin studies as epigenetic
phenomenon and dynamic transcriptional alternations that leads to changes in the gene
expression that is observed in MZ and dizygotic (DZ) twins. To understand the aetiology of
illness, twin studies are beneficial that put special emphasis on genetic and environmental factors
underpinning variations in susceptibility to various diseases. A study conducted by Naukkarinen
et al. (2012) highlighted the fact that obesity is not only influenced by lifestyle factors, but also
due to genetic predispositions. This unique experiment revealed that MZ twins that are
discordant for obesity are as ‘clonal controls’ of non-obese and obese individuals that has
enabled the characterization of possible antecedents of acquired obesity. The study also pointed
to the predisposing candidate genes that are novel to obesity. A number of studies were
conducted in order to measure twin correlation. Form the different heritability studies conducted
it was found that the monozygotic correlation was twice the dizygotic (Poduri et al. 2014). As
commented by Kandler et al. (2015), the resemblance between parents and offspring are mainly

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due to additive genetic variation. As argued by Seyerle and Avery (2013), it is not the shared
environment but the amount of overexpression of an allele which affects the overall growth
pattern of an individual. Study through different filial generations have pointed towards the
inheritance of single nucleotide polymorphisms (SNIPS) to be one of the prime causes of
phenotypic variations between twins. Autosomal single nucleotide polymorphism studies have
supported the fact that 17% of the variance in BMI could be explained with the help of sequence
variants in the genome (Kandler et al. 2015).
Myopia is one of the major reasons for impaired vision worldwide. Research and analysis
have pointed at the importance of twin studies in establishing the hereditary link to myopia. Twin
studies have reported high heritability for refractive error of up to 90%, whereas family studies
have pointed that up to one –third of population variance is attributable to the effect of shared
family environment (Schilit and Nitenson 2017). As mentioned by Nordström et al. (2016),
ophthalmologist traits were found to have the highest heritability. Twin studies have been
beneficial in relating factors such as corneal thicknesses between siblings. The tight correlation
found between identical twins helps in understanding the genome wide differences and their
expressivity in no-identical twins and the effect of different environmental factors (Seyerle and
Avery 2013).
Ethical dilemmas related to twin studies
There are a number of ethical dilemmas in using humans as subjects for conducting of
twin studies. First and foremost consent needs to be taken from the twins for involving them as a
part of the stud as they should not be made participate forcefully. Additionally, while doing the
analysis if an individual is given a more positive opinion compared to their siblings that might

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develop a feeling of inferiority or low self esteem within the individual. As commented by
Huppertz et al. (2014), conducting a twin studied often means that extensive family details are
need to taken for drawing out a perfect correlation. However, often the participants are not
willing enough to share the exact details which may hamper the quality of the study and the
results. Additionally, there are privacy and confidentiality issues which need to be shared with
the participants in an effective manner. While conducting the research the participants may
come face to face with a number of serious health concerns of the patient. As per the research
ethics the participants have the right to know regarding the test results and the researchers should
not hide the required amount of details.
Conclusion
The current research talks about the benefits and dilemmas related to twin studies. The
twin studies helps in understanding the genetic variability patterns. Additionally, it helps in
understanding the effects of evolution better. However there are a number of dilemmas which
further affects the pattern and correctness of the results produced. Twin studies provide powerful
data to the researchers as it provides better determination of whether a particular illness, trait or
disorder is influenced by genetic factors or due to environment.

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References
Huppertz, C., Bartels, M., Jansen, I.E., Boomsma, D.I., Willemsen, G., de Moor, M.H. and de
Geus, E.J., 2014. A twin-sibling study on the relationship between exercise attitudes and exercise
behavior. Behavior genetics, 44(1), pp.45-55.
Kandler, C., Lewis, G.J., Feldhaus, L.H. and Riemann, R., 2015. The genetic and environmental
roots of variance in negativity toward foreign nationals. Behavior genetics, 45(2), pp.181-199.
Nordström, P., Pedersen, N.L., Gustafson, Y., Michaëlsson, K. and Nordström, A., 2016. Risks
of myocardial infarction, death, and diabetes in identical twin pairs with different body mass
indexes. JAMA internal medicine, 176(10), pp.1522-1529.
Poduri, A., Sheidley, B.R., Shostak, S. and Ottman, R., 2014. Genetic testing in the epilepsies—
developments and dilemmas. Nature Reviews Neurology, 10(5), p.293.
Schilit, S.L. and Nitenson, A.S., 2017. My identical twin sequenced our genome. Journal of
genetic counseling, 26(2), pp.276-278.
Seyerle, A.A. and Avery, C.L., 2013. Genetic epidemiology: the potential benefits and
challenges of using genetic information to improve human health. North Carolina medical
journal, 74(6), pp.505-508.

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