The biological approach is based on the idea that depression has a physical or organic cause. One explanation suggests that some people are simply more genetically inclined to develop depression, as Hecimovic suggested that it was caused by a mutation in the 5-HTT gene, which was responsible for coding for serotonin production, and that this mutation is inherited. Family studies, twin studies and adoption studies have all helped support the role of genetics in the development of depression. Gershon found that if a parent of a child had depression , that the child was then 2-3 times more likely to suffer from the disorder themselves. Twin studies, conducted by McGuffin found that the concordance rate of twins varied, depending if they were monozygotic or dizygotic. If depression is linked to depression, then it would be expected that MZ twins have higher concordance rates as they share 100% of the genetic information. He found that MZ twins had a concordance rate of 46%, while DZ twins had a concordance of only 20%. Lastly, twin studies done by Wegner found that children are 8 times more likely to develop depression if their biological parent also suffered than if their adoptive parent did, suggesting that depression is greater influenced by genetics rather than environmental factors.
A major flaw of using twin and family studies however, is that the participants are often still sharing the same environment, which could have more of an influence than the shared genes. Nevertheless, the findings from adoption studies, which don’t have the issue of shared environment still show similar results, suggesting that genes but play a significant role. Moreover, a flaw with the research by Gershon is the limited sample size, as he only reviewed ten families, suggesting that results may be unreliable and we may not be able to generalise the findings to a wider population.
Another biological explanation into depression is the role of