Due date: 2nd May 2013
Name: Veronica Pedersen
Student ID: S2858555
Tutor: Mr Riyad Rahimullah
When determining and discussing the question “how adoption and twin studies have influenced the nature versus nurture debate” it is important to identify the key terms. The nature versus nurture debate is an ongoing debate focusing on how much our environment (nurture) and our genes (nature) affect us as human beings. Twin studies (studies involving twins) help to determine the importance of environmental and genetic influences on individual traits and behaviours (Wright, 1997). Other groups that are useful in the studies of genetic similarity include full siblings and adoptees. In discussing how adoption and twin studies have influenced the nature versus nurture debate This paper intend to examine the terms and have a closer look on different adoption and twin studies. Showing how these studies both benefits the nature side and the nurture side of the discussion. This essay will argue for the importance in which the adoption and twin studies have had for the nature-nurture debate.
The nature versus nurture debate is an ongoing one. The debate is a controversy about the effects of biology and social systems on individual’s behaviour. The “nature” side argues that people are shaped primarily by genetics and biology. The “nurture” side argues that our participation in social life is the most important determinate of who we are and how we behave (Moore, 2001). When trying to find the “answer” to why humans develop differently, adoption and twin studies is an excellent way of studying if it is nature or nurture that makes us who we are. The nature versus nurture debate has identified issues and by using this research, there is now a new view; it is not primarily our environment and the genetic structure that are responsible for our behaviour it is both.
Twins are a valuable source of observation because their genotypes and family environments tend to be similar. Behavioural geneticist break down the vast term “environment” into two parts, shared and non-shared. The shared environment is what twins or other siblings have in common; their neighbourhood, church, social status and the child-raising techniques. The non-shared environment is whatever those siblings do on their own time (Turkheimer & Waldron, 2000). Monozygotic (MZ) more commonly known as “identical” twins share nearly 100% of the same genes and are therefore very helpful when looking at the nature side of the debate. Dizygotic (DZ) or “fraternal” twins share only 50% of the same genes and are no more similar than two siblings born after separate pregnancies (Bouchard, 1999). Fraternal twin studies are helpful to study because they tend to share many aspects of their environment. Due to the fact that they are born at the same time and place, they often share the same environment, culture, community and parenting style
Twin studies provide support for researchers to separate the environmental and genetic influences on individual traits and behaviours. An example of a twin study is a study conducted by Koeppen-Schomerus, Stevenson and Plomin (2001). The aims of this study was to test a large sample of 4 year old twins to see if there was a bigger connection between genetics or environment in developing asthma. The sample consisted of 4910 twin pairs: 1658 monozygotic (MZ), 1651 dizygotic same sex (DZss), and 1601 dizygotic opposite sex (DZos) who were born in England and Wales in 1994 and 1995. Data on asthma status were obtained from the twin’s parents by postal questionnaire. The result where that when developing asthma they estimated it to 68% heritability, 13% shared environment and 19% non-shared environment. These findings indicate that asthma is highly heritable (Koeppen-Schomerus, Stevenson, Plomin, 2001). This study shows that by using...