Question

What are the advantages and disadvantages of using twin and adoption studies to assess the effects of genetic and environmental factors?

Answer 1

Twin studies are way of studying the genetic influence of a trait or disorder. Twins can be dizygotic sharing the same dna as any other siblings and monozygotic having a completely identical DNA.Adoption studies investigate the similarities between the adopted person and their biological and adoptive parents.

Advantages of twin and adoption studies are -

• Both Adoption and Twin studies provide the data of both genetic and environmental factors.
• Twin studies provide a natural experimental design.

• Difference in concordance rates of monozygotic twins who share 100 % dna and dizygotic twins who only share about 50 % dna provide clear evidence of genetic influence.
• Adoption studies can overcome the barrier of equal environment which is present in twin studies ,where they live together.

Disadvantages of twin and adoption studies are

• Selective Placement - The adopted childten are generally placed in a family similar to the birth family making it difficult which can artificially increase the estimate of environmental influence.
• Twins are born at the same time , become the same age together and share a more similar environment than just siblings, leading to environmental factors being counted as biological factors.
• Sample size for identical twins and adopted chilchildren is relatively low.
• Contacting the biological family of adopted child can lead to ethical problems.
• adopted child and both sets of parents may not necessarily be representative of general population.