Siblings scrapping over who did what to who and who's really to blame can drive parents mad but these spats are normal and necessary, says psychologist Dr Rachael Sharman.
"Your family is a little microcosm for society where the kids are trying to jostle to figure out 'how do I actually work with other people and learn how to play well with others?' she tells Susie Ferguson.
In the younger years, squabbles between siblings are all about the quest for parental attention, Dr Sharman says.
"We like to think we're a sophisticated species but we're really like birdies in the nest squawking for our parents' attention,"
When children are a bit older, the conflict between them is more about asserting power.
If this becomes a pattern it can be a red flag for bullying, which quite often goes unnoticed when parents are stretched too thin.
"If a younger sibling is withdrawing, seems scared of another sibling and a bit too isolated, it's time to start asking questions, particularly if you're not always there to monitor what's going on."
An age gap between siblings can complicate things, she says, especially when an older child becomes resentful of having to look after their siblings or carrying too much responsibility in the family.
If an elder child is male and has "antisocial tendencies" they may even need to be kept from spending unsupervised time with their younger sibling.
But Dr Sharman warns parents against mistaking a child who is more exuberant than their family members for a bully.
"The kicker is here - is that child repeatedly trying to use power in order to get control over their siblings? Or is it just someone who's a bit louder and has a bigger presence because of their personality?"
Kids have a powerful radar for unequal treatment, she says, so it's important that parents give as much time and attention to children they don't happen to share personality traits and interests with.
To the parents of kids who seem to have no common ground at all, Dr Sharman has the message that sibling relationships are, hopefully, a long game.
"Sometimes you have really different distinct personalities in there who at the end of the day don't get on very well but will [eventually] tolerate each other at Christmas."
Dr Rachael Sharman is a senior lecturer in psychology at the University of the Sunshine Coast.