One of the oldest controversies in psychology is nature versus nurture. The whole debate comes down to genetic inheritance or environmental factors when it comes to human development. The philosopher Plato believed that certain behaviors are innate or, in other words, occur naturally regardless of environmental factors. Then there are other philosophers like John Locke who believe that the mind begins as a blank slate. So everything we come into contact with helps shape who we are. Today, most people believe that behavior and personality are influenced by both nature and nurture. Some examples of genetic inheritance are the color of your eyes, straight or curly hair, the pigmentation of your skin, and certain hereditary diseases. Not all people with blonde hair are the same person, and not all members of a family have the same hair color or eyes. An example of an environmental factor that affects who you are is how you were raised by your parents. Another example of an environmental factor that helps influence behavior is the way you speak, you learn the tone, speech and sound of the people around you when you are a child. (Knowlton, 2005)Studies.The first study I found on Nature vs. Nurture was the Swedish Twin Study of Child and Adolescent Development, also known as CHAD. This was a longitudinal study of how genes and environment can contribute to the development of health and behaviors. This study was one of the largest twin studies ever conducted. It collected data from 2,960 people, 1,480 pairs of twins and their parents aged over 16. The last time data was collected on the subject was in 2005, when children were turning 20. The primary goal of this study was to examine externalizing symptoms such as criminal behavior, ADHD, a...... middle of paper ......transmission from parent to child has little effect on his later cognitive abilities. (Plomin, Fulker, Corely & Defries, 1997) In these two studies, researchers used infants and children to prove or disprove the biggest controversy in psychology today. The main similarities between these two studies are that they both used children, they both followed children over a 20-year period, and they both used intensive surveys and questioning to learn about results. The major differences between these two studies were that the first study used identical twins and the second study only used children who were going to be adopted. Then, in the first study, we tried to prove whether aggressive behavior and mental disorders were caused by nature or by nurture. The second study wanted to prove that adopted children tend to behave more like their adoptive parents..