Abstract
The paper discusses the two most common types of twins; identical and non-identical twins, also known as monozygotic and dizygotic twins. The paper looks at the differences between identical and non-identical twins. The paper then talks about a third type of twins; half-identical or polar body twins.

Outline:
What Are Twins
Types of Twins
Identical Twins
Comparing Non-Identical Twins with Identical Twins
A Third Type of Twinning

From the Paper
"In a normal pregnancy, a single baby develops in the uterus of the mother. In very special circumstances, two and sometimes even more babies develop simultaneously in the mother's uterus. This is called a multiple pregnancy. Twins are two babies in a multiple pregnancy. Twins are considered very special and present a fascination for science and society. In the fields of psychology and sociology, there is a special subfield called "twin studies". Twins studies are especially important in the search for answers to the nature vs. nurture question. What is the most important factor in human development: genetics (nature) or environment (nurture)?"

Tags:multiple, births, monozygotic, dizygotic, zygotes, embryos

Abstract
This essay discusses the research into anxiety disorders. The study under examination does research with same-sexed twins. The authors look into genetic factors in the creation of anxiety disorders. They do this in a study of 32 monozygotic (MZ) and 53 dizygotic (DZ) adult same-sexed twins. In their study, the frequency of anxiety disorders turned out to be higher in MZ than in DZ twins.

Abstract
This essay examines the role of genetics in schizophrenia making reference to several monozygotic and dizygotic twin case studies as well as adoption studies. The influence of pre-natal environment on schizophrenia and brain imaging as confirming a physiological basis for schizophrenia are also dealt with in this essay.

From the paper:

?When looking at possible genetic causes for a disorder as complex as schizophrenia, the researchers must control as many variables as possible. They cannot control the possible influences of neonatal events, child rearing or other life events that might contribute to the person?s mental state.?

Tags:psychotic, mental, illness, cognitive, functioning, thinking, emotions, behaviors, motor, control, research

Abstract
This paper explains that, instead of studying personality from the traditional "nature versus nurture" approach, many psychologists, biologists, sociologists, and geneticists are beginning to examine the complex relationship between genetic, behavioral and environmental effects rather than just focusing on the differences. The paper specifically describes research projects that examine these assumptions of inter-relationship. The paper concludes that an individual's personality is truly unique in that it involves a dynamic interplay between both the individual's definitive nature and manifested nurture.

From the Paper
"The study of identical twins is definitely an interesting method of researching the effect of the genetic inheritance, which is acquired before birth, and the surrounding events and conditions one is raised in after birth. It is quite evident that behavioral genetics will continue to be of great importance in the future of many areas in psychology. It will definitely prove to be of special concern and interest to the field of personality, as advancements in identifying specific genes associated with certain variations in personality and mental abilities are discovered."

Tags:monozygotic, dizygotic, child-rearing, twins, heredity

Abstract
This paper examines the multitude of issues related to crime and more specifically, the fundamental relationship between genetics and crime. It evaluates the three distinct methodologies (adoption studies, family studies, and twin studies) that are used to discover the correlation between genetic influences on antisocial and criminal behavior. It also reviews different twin studies and their correlation to antisocial and criminal behavior. It concludes with recommendations for finding solutions to the crime problem.

From the Paper
"Few issues are as controversial and difficult to resolve as crime. Over the past 20-25 years, public concern over certain aspects of the crime problem has intensified. In particular, law enforcement and the public have focused on the challenge of supervising parolees and probationers in the community, juvenile crime, the role of television in producing violence, and urban gangs. Researchers have found a causal relationship exists between crime and such traits as: age; economic status; education level; environmental factors; ethnicity; gender; genetics; intelligence (or lack thereof); psychological factors; race; sex; sociological factors; etc."

Tags:criminal, behavior, dizygotic, twins, monozygotic, genetic, etiology, law

Abstract
This paper presents a detailed exploration of the autism disorder. The writer explores what it is and how it manifests itself. The paper also discusses the teaching methods that have been used to allow the autistic student to take part in public education. The author makes use of graphs and tables to illustrate certain points throughout the paper.

From the Paper
"Studies have also uncovered genetic factors in autistic male triplets in Sweden and in England. The degree by which the triplets were affected by the autism did vary in the English study according to the published results. One of the things that researchers have been looking at is the incidence of autism among the general population as compared to the degree and frequency of autism among autistic siblings. The studies indicate that there is a higher incidence of autism among children who have a sibling with the disorder than there is in the general population.
In the effort to locate causes of the disorder one study provided additional B6 to autistic children in a double blind cross study. The results indicated that the B6 was helping autistic children reduce their symptoms where as the non vitamin group had a reported worsening of symptoms."

Tags:IQ, dizygotic, monozygotic