Take Nick and Tom Inatey for example. The brothers have a two year age gap between them and have been trying to one-up each other since they were young.
Nick says their competitiveness really grew throughout their teenage years and peaked while they were in university, when Tom's achievements just kept pilling up to the point that it became a family joke.
Tom explains: "It comes from a time in our lives, probably when I was about year 11 to early university ... most goals that I set or most things that I wanted I managed to achieve somehow and to Nick it seems like there was a rainbow effect and dad kind of encouraged that along just by poking fun at it from time to time."
From awards at school to comparisons with their jobs, the Inatey brother's rivalry has continued into adulthood.
"I think the competitions become a little more accentuated within a healthy boundary of course ... We still refer to the Thomas Rainbow thing more just in jest but of course, in some ways it probably inspires us to outdo each other but at the same time try and outdo ourselves a little," Nick says.
Then there's sisters Melanie Colwell and Jen Paull who seem to be polar opposites of eachother.
We've all heard the stereotypes about siblings. The elder is more domineering and in control, the middle might be a bit lost, and the youngest is more exploratory one and more spoilt.
"I was extremely teacher's pet, straight As, quite straight-laced and Jenny was extremely rebellious. I think she thought that I was pretty boring and uncool. I was also quite fearful of the consequences and respected authority and that sort of thing and Jenny was so sort of free spirited and confident. I was quite envious of that aspect of her personality," Melanie says.
Melanie said she doesn't think her parents knew "how good they had it" until Jen was born.
"Having said that, Jen was so much younger and you know, the youngest child obviously always gets away with more."
Conversely, Jen has described her elder sister Melanie as "a role model" who was "pretty perfect".
"I grew up basically wanting everything that she had ... I saw her as the favourite, even though I'm not sure if she was. I was a bit of a rebel compared to her and I would do anything to break the rules," Jen said.
Insight guests (from left) Jen, Melanie, Nick and Tom. Source: SBS
Sibling relationships can play a significant role to the development of social and emotional skills and have a huge bearing on the way people see their place in society. It's not uncommon for siblings to fight, but at what price does this come at?
University of Queensland academic says it's a very fine line between robust rough and tumble versus bullying in the sibling relationship.
"Sibling rivalry and conflict is a very normal thing, in fact a very healthy thing and it can be very productive. I think the idea of dealing with the fact that you might not be first, that you need to be second is a life skill and the sibling relationship is really important one for that.
"When you get along well with your siblings and the parents are involved in the right way, how it can really set you up for life and learning how to solve problems, how to negotiate, how to deal with disappointment."
"But it can spill over into that point where it's marked by, you know, physical aggression, hostility. When it's persistent that's the sort of time where we need to be thinking about getting involved because I think the effects of this conflict can be quite serious."
University of Queensland's John Pickering. Source: SBS
When should parents get worried about their kids' behaviour? And should they intervene during a conflict or let them learn to negotiate and self-regulate their behaviour?
"There is a line and of course you can see that I think particularly physically when there's hurt involved. Emotionally it can be a bit more difficult. Often children depending on their age can tell you. But parents need to exercise judgement," John Pickering says.
Is there a difference between the kind of tension within siblings and the sense of betrayal with a friend?
Professor from Macquarie University believes so, even though competition is inevitable within the family unit.
"A sibling betrayal can be even more heartrending and hurtful because of the expectations we have about family.
"Siblings are allies because they share their genes, they share a common interest but the interesting thing is that the family is a united front. We are expected to unite and to demonstrate loyalty to our family when times are very tough ... the expectation is that we will stand up for our brothers and sisters and we'll protect them.
"So there's a lot of allyship within a family but that also means that if a family member breaks the rules then it can be very dire and perceived as a very dire betrayal ... the research suggests that that's considered the worst thing. That's the kind of bottom line, is you pull together when it really counts and all your internal squabbles at that point become less important. "
Professor Julie Fitness is head of psychology at Macquarie University. Source: SBS
Despite it all, for the Inatey brothers, both Nick and Tom are comfortable about the state of their relationship.
"We're not the kind of brothers that we'll call each other all the time and share news what's going on. Nick was there for me when I needed him the most in my life and like I'll always cherish that and always love that ... At least for my part, I don't feel we need to be close to Nick for our relationship to be strong. I think it's strong as it is," says Tom.
Similarly, Melanie and Jen both believe their sisterly connection is an enduring one.
"We've got such a big age gap ... we're so different, you know, we don't really hang out together ... we're not the type of sisters who go shopping and do coffee, see each other three times a week. But having said that, our bond is incredibly strong," Melanie says.
Jen adds: "We've stuck together, we there through thick and thin for each other no matter what, so yeah, I think that will last for a long time."
On , we ask our guests: Is the sibling bond stronger than any other? How do you forgive your sibling when they have betrayed you? Are such disputes unavoidable, and do tensions always persist into adulthood?