We share the same DNA but are worlds apart

Brought up in the same household, by the same parents, experiencing the same childhood yet it is a constant topic of conversation between me and my brother that we really are quite different.

Growing up with a brother four years older than me, I spent my childhood constantly wanting to catch up with him. I was the designated goalkeeper as he pelted footballs my way and I constantly seeked his approval because he was the cool big brother and I was just the little sister. 

When asked if me and my brother are similar, without hesitation it is a no. On first thought we are worlds apart, something that was not as prevalent in our childhood but more so now we are older. But when I think about it, it is all surface level stuff, interests, music taste, shows of choice- although thanks to his girlfriend we can both discuss Bridgerton in great depth. 

Who else is better to give insight into our differences than Morgan himself. ‘‘Initially, I would have said that my sister and I are very different people with very different personalities. In fact, it’s been a running joke in our family for a while about how different we are. I avoid the sun, Gabriella’s the first one out there on a sunbed. Maths was my strongest subject, Gabriella’s was English. My sister thrives on the energy of social gatherings, while I prefer the quiet comforts of home with a good book. On the surface, we’re very different but these differences are more about our personal preferences than personality.

‘‘At an innate, human level who we are as people and how we face the challenges thrown at us, we’re more similar than we both probably think. We both get stressed if there isn’t a clear plan in place, we’re both empathetic and we both need time alone to recharge, I just need a lot longer.’’

And he’s right, the similarities are there but on a day to day they often get overshadowed by our more prevalent superficial qualities. Our most prominent difference is the need for social interaction. As Morgan said, we both require time to recharge the social battery but for me socialising is a necessity whereas for him it’s a nonessential. So, just why is it that we can have these differences? 

‘‘Siblings share only about 50% of their DNA, this might seem like a lot but chimpanzees and humans share about 96%. One reason that there can be differences is that despite having lots of the same DNA in common, you are not ‘wired’ in the same way,’’ says licensed clinical social worker, Toni Teixeira. ‘‘We are all born with different temperaments, an innate quality that is not determined by genetics alone. The difference in personalities in children is because they come into the world with different temperaments and are exposed to parents and other people who also have different temperaments.’’ 

Teixeria’s words make a lot of sense, mine and Morgan’s fundamental differences can be explained simply because we have been wired differently. But with only four years difference is it possible for our parents’ temperaments to change that much? 

‘‘Parenting style will influence child development, and as parents learn and grow, the way they interact with their children may alter over time,’’ says Dr Amber Johnston, clinical psychologist and director of Healthy Mind psychology. ‘‘It means that different children may experience different levels of empathy, understanding, expectation, or unique support as the parents become more in-tuned or practised in their parenting skills during specific developmental milestones for each child.

‘‘The same home environment does not mean that children will have the same experiences with which to learn from. Even similar parents will interact and react to children differently for a host of reasons. Children may be quickly labelled as different types of kids and then others may respond to them in ways that fosters that identity- and therefore differences between siblings.’’ 

When I asked my mum about mine and my brother’s differences it was clear that even from day one we had different ways of processing the world. I was a lot more of a chill baby, in her words a very low maintenance child, and Morgan not so much…sorry Morgs! And I think those differences have maintained even in our adult years, our similarities are there but you can always rely on me to be the calmer sibling.

‘‘As children encounter experiences within a wider world, their brains are learning about the most important thing a brain can learn- what keeps a person safe and surviving,’’ says Johnston. ‘‘As our brain is a structure designed to protect our survival, it can develop unconscious reactions to various threats it encounters. Each child on his or her individual journey may respond in very different ways because of the cumulative learning that has occurred up to the point of that incident. The stress response may be activated earlier or later in different siblings, and their own perceived ability to influence the situation successfully or be helpless will develop their behaviour and personality traits,’’ says Johnston. 

It is clear that siblings are not meant to be similar, if anything it’s seeming more common for us to be different. While me and my brother may have the same eyes, mannerisms and hair texture, our differing temperaments which are not controlled by genetics shape us into the unique individuals that we are today.

Expert insight: Dr Amber Johnston

Dr Amber Johnston is the director of Healthy Mind Psychology and specialises in clinical, health, pain management, and neuropsychology.

Expert insight: Toni Teixeira

Toni Teixeira is a psychotherapist at Strong at the Core Counselling and a licensed clinical social worker who helps people navigate trauma and has training in internal family systems.

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