Will human clones think alike?
Updated: Dec 11, 2018
My answer would be...most probably not.
First, let’s examine the reasons for this claim. Yes, it is true that the brain structure of a clone will be largely influenced by genetics, the cortical complexity of which could influence one’s cognitive ability. Moreover, this genetic predetermination is found to influence certain brain regions and not others, thus suggesting that each person indeed may have a unique brain structure that, if cloned, would resemble the clone to a large extent. This highly supports the role of genetics in similar brain structure and thus identical structural responses.
However, the main counterargument that largely nullifies the ‘identical’ nature of cloned personalities is the impact of the clone’s environment. Think about it as a nature vs. nurture debate, except that nurture undeniably will have an impact on the characteristics of the clone. The influence of the environment is based upon a concept known as neuroplasticity: Essentially, ‘neurons that fire together wire together’ - implying that the more you are exposed to or perform certain behaviors, the stronger is your ability to do so (classic research examples include taxi driving, juggling and playing music), and these behaviors are largely dependent upon one’s environment. Therefore, unless the clone is brought up in pretty much the exact same environment as the original human, the chances of identical personalities is quite slim.
In addition to practice of a particular behavior, another related factor driving one’s personality includes reward-punishment associations created by one’s surroundings. At birth, neurons are randomly firing in the brain (which explains babies’ random movements), until, by associations and reward or punishment, babies learn to develop specific neural pathways that fire (or do not fire) in certain manners . These associations are created primarily by outside influence - ranging from the nutrients and heartbeats of the mother, to the kind of behaviors of the species they are raised with.
Building upon this argument, I would theorize that epigenetics comes to play with regards to brain development. Evidence has shown that the manners by which an animal is treated in its early years can influence the expression of genes. This is seminal: Even if the same genome were to be implanted in a host mother, their expression can still potentially change, consequently resulting in differing behaviors such as innate hunger (for children born under underfed circumstances), or lower self-esteem. Thus, despite identical ‘DNA’ due to cloning, it is still difficult to guarantee the same gene expression occurring within the clone itself. Below are the results of a study showing changes in DNA methylation in rhesus monkeys raised from either a true mother or a surrogate :