Genetic inheritance: nature and nurture
How much of ourselves is because of the genes we inherit rather then the environment of our upbringing has been at the centre of the ‘Nature’ vs ‘Nurture’ debate for over 100 years. Although the Victorian scientist Francis Galton studied this in some detail, in the post-genomic age we now know much more about how genes control much of our physical appearance and aspects of our long-term health.
Scientists are less certain about the role of genes in aspects of our behaviors and intelligence as well as our values and interests. Twinning studies, where identical twins have been separated at birth and brought up in different families, have often been used to try and disentangle the influences of genetics (nature) from environment (nurture). These have suggested that aspects of behaviors such as addiction, linguistic ability, and even choice of which bread to eat, can have a strong genetic component.
Some critics disagree with this kind of study and point out that in some cases the data is open to interpretation. They point out that in the same way that we convince ourselves of similarities with others through a common star-sign, that when comparisons are made between genetically related individuals it is easy to dwell on obvious similarities and ignore behaviors that are different. Moreover, when genetically related individuals meet each other, it is only natural to make bonds and start mimicking mannerisms in an attempt to get on.
Jo-Ellen will only share half of her genes with her donor-conceived siblings, yet we see some striking similarities in their appearance. In the film, the siblings discuss their eyebrows and the similarities in the shape of their big toes. This is probably because of dominant genes inherited from Jeffrey determining these characters and that is easy to understand.
With regard to shared-behaviour, however, we would not expect such strength of association suggested by twin-studies. Yet in the film the siblings discuss how alike they are in many respects, such as a love of animals and their short attention spans. Whilst it may be the case that genes are strongly influencing these characters, they might also be the kind of character are commonly seen among unrelated individuals of a similar age.
The question is, what do you think?