Yesterday I went to see a movie called “Three Identical Strangers”. It’s the story of three identical male triplets separated at birth and reunited at the age of 19. As a genetic counsellor I often ponder the question of nature versus nurture and this movie investigates this theme superbly. Identical twins and triplets are born with the same genetic make-up. However when these type of siblings are reared apart, there is an argument that this informs or gives an indication to which traits or attributes have a strong genetic or hereditary component and which ones are more due to one’s environment.
Research tells us that the most rigorous experiments or studies are ones called “randomized control trials” where a group of participants are randomly assigned to being an active participant or being a control. In medicine we see this type of trial where a group of people with the same condition are randomly divided into receiving either a medication or treatment under investigation or they are given a placebo and are what are known as controls. However with adoption studies, because we have modern day ethic committees who oversee all research conducted, a researcher cannot randomly assign newborns to being either adopted or to stay with their birth parents so observational studies are performed. This is where people “assign” themselves and researchers observe differences.
In psychology, these types of studies were conducted to measure personality or behavioural traits such as extroversion and psychological disorders such as depression. I am often asked if conditions such as autism or depression are “genetic”. When people say “genetic” in this context, they mean is there a strong inherited link. Science is not at the stage where there is a simple genetic test for traits or conditions like depression or autism. In reality, like most things, there is a combination between genes and environment; we may be born with a predisposition however how we are brought up or what we are exposed to can greatly influence the development of these attributes.
People are amazed with how identical twins (either separated at birth or not) are similar. I feel that these similarities are encouraged and reinforced. Twins separated and reunited like seeing what they have in common. It reminds me of when people start a new romantic relationship, couples dwell in what they have in common. It is not usually until later do couples consider how they are different.
Isn’t it lovely that we as humans have influence on what we experience or how we are as people? Our personalities and our traits and what makes us, us are not set in stone. It can change. We can change. If we have three copies of chromosome 21 we will have Down syndrome or if we have two serious mutations in our CFTR gene we will have cystic fibrosis. However if both of our parents have schizophrenia, it does not mean that we will also have this illness. If many of our relatives are outgoing, it does not mean that our children will be too. Three Identical Strangers is a fantastic documentary combining the things that I love; genetics, psychology, the theme of nature versus nurture and ethics. If this sounds like your cup of tea, check it out!