Siblings Share Genes, But Rarely Personalities
Why is it that even though siblings share very similar genes and environment, their personalities are so different? A researcher named Robert Plomin sought to find the answer. When performing a study on siblings, he saw that siblings differ to some extent, but they were much more similar in physical appearance and cognitive abilities on average than when compared to children picked at random from the population. When it came to personality, however, siblings were only similar to each other about 20 percent of the time. There are three major theories as to why this is the case.
One, it may be explained by divergence. Divergence is a concept founded by Darwin whose role is “basically to minimize competition so it's not direct. And that leads to specialization in different niches”, according to a Darwin scholar named Frank Sulloway. Children in a family are competing against each other, consciously or unconsciously, for the “time, love, and attention of their parents”. Therefore, if one child surpasses the other in sports, then the other sibling will try to excel in another area (such as academics), in order to “avoid direct competition”. These circumstances lead to differences in personalities between siblings.
Another explanation for this phenomenon may be what is called the “non-shared environment theory”. This theory suggests that although siblings are growing up in the same biological family, they are not having the same experiences due to age differences. For example, if two siblings are 3 years apart, their family is not going through the same emotional or financial circumstances when the first sibling was 10 years old compared to when the second sibling is 10 years old. It is as if they are growing up in completely different environments.
Lastly, this may be explained by the “comparison theory”, which proposes that “families are essentially comparison machines that greatly exaggerate even minor differences between siblings”. A great explanation is put forth by Susan McHale, a researcher at Pennsylvania State University—“Imagine two friendly children born in the same family. One of those children is incredibly extroverted, and the other is just very sociable… In the context of any other family, the second child would be considered an extrovert. But in this family… she's the introvert." Because this label, the second child chooses different friends and activities, making this child different in personality from her siblings.
I really liked this article. I mean, even though it sort of states something obvious, that our siblings are different from us, it was enjoyable to read and relate. It also makes me think of twins and triplets because even though they do not have age differences and did in fact grow up in the same environment (most of the time), they can still have some different personalities BECAUSE they grew up with a sibling.
ReplyDeleteMy aunts are fraternal twins and they can be very similar in their jokes and outgoing-ness, but in their baby pictures (just about every single one) Tina was always smiling and laughing and Terri was always crying and angry. Hilarious in retrospect but frustrating at the time. Since they were siblings, they would fight, and because Terri was the squeaky wheel whose complaints were heard, her actions were reinforced. And these traits have grown with them; now one is more prone to getting upset easily while the other is good at letting things go. What could have been small and possibly changeable traits have now become cornerstones of personalities. All because they always had each other.
Until I read this blog, I had not noticed the exact things going on between my siblings and I, which are noted on this article. I mean now, once I read it, it makes sense to me. The different choices of interest, different times of growing up in the home, and labeling, it all seem to fit within, not just my family, but all the families.
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