When siblings are like chalk and cheese

When siblings are like chalk and cheese

How is it that one of your kids is happy to sit quietly and play in a focused way while your other one will chew the furniture if she spends more than an hour inside? One rarely throws a tantrum while the other regularly prostrates herself on the floor screaming.

It’s not rocket science to realise that children from the same parents not only can be, but often are, completely different in personality. And while this may be a challenge when it comes to parenting at times, and can mean we need to adopt multiple parenting styles, there are many factors which contribute to these differences – and it can be worth understanding these.

It’s genetic

When it comes to personality, the jury's out on how much of a role genes play, but the figure often bandied around is that 70 percent is genetic – leaving the other 30 percent to be nurture and environment.

For example, the inheritability of shyness and other anxiety-related behaviours is estimated to be somewhere between 40 and 60 percent, according to many studies. Intelligence, which can bring with it its own personality issues, is also believed to be highly inheritable.

Conditions that can affect your child’s temperament, such as anything along the Autism Spectrum Disorder, ADHD and even dyslexia, are also believed to be highly inheritable, so it can be worth knowing you and your partner’s family history when trying to make sense of the littlies.

Birth order

Where your child is born within the family can play a huge role in their temperament. On this many psychologists and academics agree – and a pile of books and papers have been written on the topic. In fact, Australian psychologist Michael Grose wrote a book which sums up some of the thinking called Why First-borns Rule the World and Last-borns Want to Change it.

Much of the advice to parents around birth order is to recognise the role it can play in your child’s temperament.

Psychologist Sally-Anne McCormack says that research has shown that eldest children tend to grow up mirroring their parents stronger values, which means that second children will often tend to adopt very different interests, passions and values.

“For example if the family has strong academic values, the eldest child is more likely to follow a similar path and aim to achieve academically. When the second child comes along, they can often sense they may need to be different to get attention, so they may be sporty,” she says.

“Parents who aren’t interested in sport may find, then, this child more difficult to understand and interact with.

“Even if you don’t ‘get’ your child or understand their passion, learn to. You may not share their passion or interests but you can show an interest in them. Involve yourself in all your children’s lives.”


The debate about whether gender differences are innate or created by our environment rages on. While the physiological differences are obvious, many of the people involved in gender studies still firmly point a finger at the gender-specific culture we are raised in.

So what that can mean is that mums and dads respond to and parent their kids according to their own innate thoughts on gender – and that can be a hard idea to break.

Recent UK research into 10 and 11 year-olds has confirmed that girls and boys play differently. Girls tend to spend time in smaller groups and engage in verbal games, conversation and socialising. Most boys play in larger groups, which lend themselves more to physically active games, such as football.

Other studies have suggested that boys are predisposed to higher activity levels as a result of androgens (male hormones) in utero. What research has revealed is that boys in all cultures around the world wrestle more, mock fight more and are attracted to themes of power and domination. 

Whatever the reason for the huge personality differences between the kids we have, the “blood is thicker than water” rule often comes into play. The constant in parenting advice from the experts is to be consistent in how we parent and understand that each of our wonderful kids is different and unique and to celebrate that rather than criticise or condemn.


This article was written by Fiona Baker for Kidspot, Australia's best parenting resource.

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