Surely this one is inarguably true? Well, unfortunately it’s one of those throwaway lines that can be really damaging and leave you short-changed in life. Of course you can’t choose your family in the literal sense. But in the majority of cases you can choose to make them your friends. Even though it can take some effort, it’s well worth it. Any psychologist will tell you that siblings grow up in competition with each other. In particular, they compete for their parents’ attention. And they work hard to make themselves different, so that they’ll attract individual notice. It’s a deep evolutionary drive that we’re unaware of, especially as children.

In some families it can drive a wedge between brothers and sisters. Which is somewhat unfair, since all that’s happening is that kids too young to know any better are just following their basic instincts. Some parents manage to respond as fairly as they can, but others struggle to manage the competition, or even seem to encourage the rivalry.

Once we’ve grown up and left home, we need to put all that behind us. Oh, I know that’s harder than it sounds, and we may not always succeed, but we need to keep working at it.

Why? Because our siblings will be with us for longer than anyone else. When our parents are gone, our brothers and sisters will have been around for longer than anyone else. They know what we’re really like – the bits we’re ashamed of, the bits we’ve hidden from the rest of the world, the bits we’d rather forget. So when we need a friend, they’ll be there, with a stronger bond than anyone else.

I know two brothers who fought as kids, like most brothers do. They played together too, of course. But somehow they carried their childhood squabbles into adulthood, and by their late twenties they barely spoke to each other. Then their dad died suddenly, and somehow, as the family came together, the two of them found that their strongest support came from each other. Since then they’ve been best of mates. They’ve learnt what old behaviours to avoid, and retrained themselves in some areas of their relationship, and they’ve rediscovered the friendship they had as children.

You have to work out what childhood patterns your relationship is falling into, and then work to change them. One friend of mine was asked – very pleasantly – by her younger brother to stop treating him like a kid. She took this on board, and next time he came to stay she bit her lip a few times. And interestingly she noticed that when she stopped bossing him around, he kept asking what to do about this or that – all things most people would work out for themselves. So she decided to have another chat with him, and explained that if she was going to stop bossing him around, he’d have to stop behaving like a child. He took the point, and she tells me they now have a much better, and more equal, relationship.

So if your sister is still trying to steal your friends, or your brother hasn’t stopped competing with you (even if it’s money or job titles these days, instead of sport or school grades), you need to make changes to break the pattern. Don’t assume it’s all their fault – it’s not. It’s no one’s fault. It’s just how families are. But we all need to evolve as we get older. Otherwise the next time we really need a friend who understands us, we’ll have deprived ourselves of the best friend of all.