genetic

• Genes are involved in an individual's vulnerability to OCD. Lewis 1936 observed that of his OCD patients 37% had parents with OCD. Also 21% of them had siblings with OCD. This suggests that OCD has a genetic basis. Diathesis-stress model that certain genes can increase the likelihood of someone developing a mental disorder but it is not a certainty. Environmental stress can also trigger the disorder.
• Candidate genes:

  Researchers identified that certain genes can increase the vulnerability to developing OCD. Some of these genes are also involved in developing the serotonin system which is a mood regulator. 5HT1-D beta is implicated in the transport of serotonin across synapses.
• strength is the strong evidence base. There is evidence from a variety of sources that suggest some people are vulnerable to OCD, due to their genetics. One piece of evidence is twin studies. Nestdat 2010 discovered that 68% of monozygotic twins both have OCD if one of them has it. Whereas 31% of dizygotic twins have OCD if one of them has it. This is because if the twins are non identical (dizygotic) they are more likely to experience different things especially if they are different genders/sex.
• Another study supports that if a family member is diagnosed with OCD then other family members around them are 4 times as likely to develop OCD as well, this is because they are likely to share similar genes. Especially if they have siblings as the siblings would have a 21% chance of also having OCD and the parent having a 37% chance of also having it (Marni and Stebnicki 2012). This suggests that there has to be some genetic influence on the development of OCD.
• OCD is polygenic:

  Polygenic is where there is not one single gene but multiple genes that cause OCD. A combination of these genetic variations can increase the likelihood of OCD. Taylor 2013 claimed that there are 230 genes that are involved within OCD.
• Different types of OCD:

  One group of genetic variation may cause OCD but so may another genetic variation. The term used to describe this is aetiologically heterogeneous. There is also evidence that suggests that different types of OCD may have particular genetic variations.
• It has proven difficult to find candidate genes, which are genetic variations that are a possible cause of OCD. There is enough evidence from animal studies that particular genes can be associated with repetitive behaviours, such as mice (Ahmari 2016). Even though mice and humans share the most genes, the human mind and brain is much more complex so it is difficult to generalise it from repetitive behaviours of animals to humans with OCD.
• limitation genetic model for OCD also environmental risk factors that can help trigger OCD. strong evidence that the ideology of genetics can make a person more or less vulnerable to the development of OCD. OCD is not entirely genetics as environmental risk factors can also trigger and increase the vulnerability of developing OCD. Cromer 2007 found out that over half of OCD clients in their sample have experienced a traumatic event. They also found that if the client had experienced one or more traumas then the OCD is more severe. means genetic vulnerability partial explanation .