If you believe everything you read, and you read everything, then you might think that the results of some scientific research published last week suggests that some people really are born lucky. That is, that your genes decide how fortunate you are when you roll a dice or play the lottery - or choose to start up your own company. Some people are born with the ability to pick the right six numbers; others bought shares in Korea just before the market slumped.

However, if you think about what genes do, and what luck is, it is clearly impossible for the two to be related. Genes carry the instructions for organisms to make proteins - that is all. Proteins, of themselves, are not lucky or unlucky. It's only prevailing circumstances that make them seem so.

Having a gene that helps your body acquire and hang on to available fat in your food was vital for the ancestors of the Inuit (Eskimo) making a long, cold land journey. It's not the same if you're living in modern America where almost every meal contains lots of fat: you'll become obese and prone to heart disease. But the gene involved is the same.

Furthermore, how can a protein on its own influence the world around us? You could argue that every dinosaur carried the bad luck gene - or at least, didn't have the good luck one - since they were all walking the Earth when a huge asteroid hit it 65 million years ago and wiped them out. But how can we be sure the same won't happen to us?

Also, if there were a "good luck gene", then it would tend to spread throughout the population rapidly: its owners would escape the sabre- tooth tigers, the Black Death, the deadly post-War flu epidemic. Very soon, everyone would have it - making us all equal.

In fact, what the research (by Professor Peter McGuffin at the University of Wales in Cardiff) really showed is that there is a genetic bias about your view of events that happen to you during your life. They polled children and their parents in Cardiff and asked them about their experiences, and their views of so-called "independent life events" - say, your grandmother being hit by lightning, and you stubbing your toe.

Now, these things can either be interpreted as a sign that the gods hate you, or that "these things happen". How you interpret it depends on your view of the world. It turned out that parents and children, especially twins, tend to take similar views.

Equally, the way you behave (which does have some genetic component) can affect both your view of the world, and the way you live: if you think your business is bound to fail, you probably won't try your hardest to make it succeed, and your gloomy prediction will come true.

In short, some people are optimists, and some are pessimists. Some have glasses that are half-full, and some half-empty. Your genes don't make you lucky: they simply help determine which of those you become. So when you don't win the lottery again this week - remember, it's not your genes' fault.