Genes and behaviour - SAQ Flashcards
Where is genetic information contained in?
Chromosomes and each human has 23 pairs of chromosomes (tightly-wound strands of DNA) in each of their cells and one of each of these pairs is from each parent.
Our DNA forms what for our body?
A blueprint for the structure and functions of our body
Genome
Used to signify all the genes an individual possesses.
Genes
Genes contain biological instructions to form protein molecules from amino acids.
Proteins
Proteins are essential to life because they are the building blocks of our brain and body.
Why do psychologists take an interest in genetics?
The development of new techniques as a result of advances in scientific technology has meant that this area of psychology research has been able to advance in recent years.
How do psychologists gain insights in gene expression role on behaviour?
Traditional technique that is still widely used today is to study how behaviour varies according to the degree of genetic similarity between relatives.
This is called relatedness. As genes cannot ethically be manipulated in humans to see the effect on behaviour, family-based studies are an ideal way to assess how genes influence behaviour.
What do correlational studies into the relationship between genes and behaviour measure?
The concordance rate of a personality characteristic or a behaviour between individuals.
This means that they look at the extent to which the pairs of individuals (usually twins, both identical/monozygotic and non-identical/dyzygotic) share a behaviour.
Concordance rate measurement
A concordance rate of 1 for a behaviour is 100% concordance, which in real life is impossible to achieve. It would mean that one twin behaved exactly the same as or had exactly the same intelligence or attitude as the other.
Concordance rates of 0.7 (70%) are considered extremely high.
A zero concordance rate means that there is no correlation at all between two people’s behaviour.
Two ways to study twins
They can assess twins who have been reared together or they can study twins who have been separated and raised in different environments.
Which type of studying twins is most attractive?
The most desirable in terms of research because if there is a concordance rate for certain behaviours between the twins that is higher than the rate in siblings (brothers and sisters) who are not twins, this suggests a genetic influence as they are being raised in different environments.
However, the strategy of testing twins reared apart is extremely difficult to implement in reality because twins are so rare and twins raised separately are even rarer.
Gene regulation
Research has indicated that the genes in our DNA are not all active at the same time and can be ‘silenced’ or ‘de-silenced’
Leads to differences in gene expression
Switching a gene off
Prevent it from making the protein it was designed to produce, cells can use chemicals in the body called methyl groups and initiate a process called methylation to block a gene’s effects.
How to switch a gene back on
Reverse process of demethylation
Epigenetics
Study of how genes are switched on and off
Study used for genetics
Bailey & Pillard
When was Bailey & Pillard
1991
How was homosexuality seen before?
Prior to research that indicated that sexual orientation may have its roots in our genetic coding, homosexuality was considered a mental illness. In some countries and states within the USA, homosexuality was illegal.
Sample
The researchers recruited monozygotic (MZ) and dizygotic (DZ) twins as well as adoptive brothers through gay publications.
All of the participants in the sample were voluntary and male.
All twins in the study were raised together – which means that we can reasonably assume that the environment was highly similar.
What did they check on the twins?
The sexual orientation of relatives was assessed either by asking relatives directly or when this was impossible, asking the gay participant who had volunteered for the study.
What did the participants have to do?
The researchers used questionnaires to assess the participants’ level of Childhood Gender Non-conformity (CGN).
Childhood gender nonconformity is a phenomenon in which pre-pubescent children do not conform to expected gender-related patterns, and/or identify with the opposite gender.
Gender non-conformity in children can have many forms, reflecting various ways in which a child relates to his or her gender.
Results
Found that 52% of MZ twins were both self-identified homosexuals, 22% of DZ twins were so, and 11% of non-related adopted brothers were so. A later study showed that non-twin brothers had a rate of 9.2%. This evidence shows that the more closely genetically linked a pair is, the more likely they both are to exhibit gay or straight tendencies.
The researchers found that the participants’ self-reported history of childhood gender non-conformity did not predict homosexuality in any of the three samples. Thus, childhood gender nonconformity does not appear to be correlated with the development of homosexuality. However, monozygotic pairs were very similar in their level of childhood gender nonconformity.
What to know for genes
Chromosomes Genome Genes Proteins Twins Concordance rate Gene regulation Bailey and Pillard (1991)
