It's one of the longest relationships we'll have with anyone so why don't we show the sibling bond a bit more love ?
Instead the connection between brothers and sisters is often fraught, beset by fighting and jealousy.
Clinical psychologist, Catherine Gallagher told RNZ podcast Are We There Yet? that people often prioritised romantic relationships, or those with their peers or children, and the sibling relationship was taken for granted.
Yet, she said, while our brothers and sisters could be "the bane of our existence", they were also a source of great fun and huge support.
"The sibling relationship is the longest relationship that we will have in our lifetimes so it's really worthy of attention and often doesn't get much."
Except, of course, when there was fighting involved and that was when it really grabbed parents' attention.
"[That is] often when people will come to me about this stuff, in terms of "How do I deal with this?" because it can be hugely triggering for parents."
A good starting point for understanding why children fought was to imagine how great the change could feel for a child when a new sibling arrived, she said.
"This little sister is going to make loud noises, poo a lot, take attention away from you. They aren't old enough to play with and Mum and Dad suddenly seem tired and grumpy."
Gallagher said all these things would take time for a child to adjust to even if a family was well prepared but the process could help build resilience.
"Adjusting to siblings can be a good model to be exposed to because it's one of many changes child's going to have in life."
And the whole business of getting on with that tiresome new brother or sister could help develop skills such as sharing, conflict resolution and coping with frustration.
"It's actually OK and, in fact, essential for our kids to be frustrated and sibling relationships are full of frustrations. So you could see as a great space to explore and experience feelings that are important as a growing human being."
And there were some lessons too for parents about how to understand sibling rivalry and manage it better.
Tips for sibling harmony
When a baby is born, head off jealousy by making time for your first child but be practical about how you can achieve that.
"You've got to be real. If you've only had two hours sleep, you're not going to be able to jump up and be perky and bake cupcakes the next day with the wee one."
Gallagher said the child's needs must be met but this could be through a quiet activity or a playdate with someone who had more energy at that particular time.
She said it was also important the child had a role as the "older" brother or sister.
If kids are fighting, split them up
She said this could shut down an argument and calm matters quickly.
"At times dividing is conquering so siblings having lots of unstructured time together can be asking for trouble."
Alternatively interrupt a fight, explain the potential consequences of continuing and leave it up to the children.
Gallagher said, if children were given a choice of stopping an argument or going into time-out they could make their own decision. "So resisting the urge to get caught up in "He said, she said". Then kids become motivated to just either sort it out quickly or move away from the conflict."
But if they're not fighting, give that positive behaviour or "quiet play" some attention.
Parents often took advantage of children playing quietly to get on with jobs and believed their children were happy to be left alone. In reality, Gallagher said most children thrived on parental attention and some well-timed praise at this point could encourage more quiet play.
"So again it's about us working out that, if I end up being around kids, praising and being physically present when they're playing nicely, that's reinforcing to them."
If a conflict developed, parents should deal with it in a matter of fact way, without giving too much attention to the negative behaviour.
Be clear about how the children are expected to share things
"For example here's the remote control. You've both got it for half an hour. Muck around with your other sibling's half an hour then you lose some time off yours." Gallagher said.
Encourage children who struggle to manage their emotions to join in
Some children found it hard to socialise easily, even if it was just with their siblings. It helped to work out what they needed to manage a social activity and plan it accordingly, Gallagher explained.
"It might be that for that particular child, they play with the bigger group, or with their sibling, for a little bit in a highly structured activity and then they come away, calm [down] and regroup and then they can go back in there again," she said.
Be realistic about how much social contact some children can tolerate
Gallagher said parents had an assumption that their children "should be able to play nicely" and if they didn't, there was a temptation to storm in and tell them off.
"Because it was what we wished for but it was never going to happen so sometimes we're setting the system up to fail."
Teach your children to understand that others, including their brothers and sisters, may be better at something than they are.
It was natural for siblings to want to compete but children had different talents and parents could want to protect them from that realisation. Gallagher said parents should help them to face it instead and this would build confidence.
"Sometimes you need to cuddle them and say "It's hard, isn't it, when you want something and you can't have it." So, not to rush into problem solving but to sit with the feeling."
She said parents should also encourage children to identify what their own strengths might be.
Allow sibling bantering as it can be the first chance to build the resilience needed when a child starts pre-school or school.
Gallagher warned that "sanitising" the home environment and protecting children too much could leave them unprepared for teasing. "Because the child is going to be completely crushed when they go to school and someone says "You've got a big nose" or "You're not so good at that". She said kids needed to be aware that other children had different skills and some of them might point that out.
But be wary of sibling conflict that goes too far and becomes demoralising for a particular child.
Parents should keep an eye on this and stamp out any real negativity, Gallagher said.
"Because there's a difference between healthy sibling rivalry and a child who is provoked and ridiculed for a lack of ability and siblings can be cruel."
Accept that things won't always be fair and help your child to cope with that
Gallagher said parents could feel pressure to make life fair for each child, especially as children were good at pointing out perceived inequalities.
"In reality, life isn't fair and, if parents can be confident that they will do their best to try to meet each child's needs, then we can step out of the fairness trap and help our children tolerate frustration which is a really vital life skill."