That's what most people - including medical professionals - think. But not Dr Nicolas Perricone, the top US-based dermatologist who's probably best known for his loyal celebrity clients (Eva Mendes and Uma Thurman are just two of the high-profile celebs who can't talk highly enough of him).
According to Dr Perricone, the idea that our genetics determine our susceptibility to disease and the signs of ageing isn't necessarily true at all. Certain foods, he says, can switch on protective genes and switch off genes that have a negative effect on your health - which is something Dr Perricone calls Nutrigenomics (the combination of nutrition and genomics).
"We are no longer at the mercy of our genetic blueprint," he says. "With the introduction of Nutrigenomics, we can change our body on a cellular level and say goodbye to wrinkled, sagging skin, excess body fat, impaired mental function and a host of hereditary diseases.
"The fountain of youth may be no further away than your next meal."
The principles of Nutrigenomics are outlined in Dr Perricone's latest book, Forever Young (Atria Books, £17.99). But to give you a taster of what it all means, here are just some of the essential foods Dr Perricone claims can 'alter' your genes for the better, which could put you in more control of your body and how it ages than you'd think...
What to eat
As Dr Perricone explains, proteins involved in your DNA called transcription factors are thought to trigger ageing and disease while others are thought to prevent them. Most people won't recognise the names of these transcription factors - not unless you're a genetics expert, that is - but to give you some idea NRF2 is a disease-fighting transcription factor and NF-kB is a disease-promoting one.
Cinnamon: Not just delicious, this spice contains heaps of antioxidants and according to several studies has a stabilising effect on your blood sugar (which, says Dr Perricone, is one of the keys to staying wrinkle-free). Not only that, but substances in cinnamon activate NRF2 (the age and disease-fighting protein).
Turmeric: A favourite with curry lovers, this is another spice Dr Perricone claims turns on NRF2. In fact he goes as far as to say that eating turmeric root on a daily basis can prevent the loss of cognitive function (including memory loss) that we face as we get older.
Spices: Many other spices suppress NF-kB (the damaging protein), says Dr Perricone, including basil, rosemary, cloves, cocoa, fennel, coriander, garlic, ginger and chillies. Turmeric and cinnamon are also NF-kB suppressors.
Cocoa: An excellent source of plant nutrients called catechins, which not only help activate NRF2 but also de-activate NF-kB. For optimum health benefits and enjoyment, says Dr Perricone, choose extra-dark chocolate made from 70-85% cocoa solids as well as, where possible, non-Dutched cocoa (Dutching is an alkalising process that reduces the amount of antioxidants in cocoa).
Blueberries: Also rich in catechins, blueberries are a significant source of nutrients called anthocyanins, which contain compounds called pterostilbenes - and these, say Dr Perricone, activate the genes that influence your longevity. But it's not just blueberries that have this effect - all colourful fruits and vegetables are also rich in anthocyanins.
Green tea: An antioxidant in green tea called epigallocatechin gallate (EGCG) inhibits the activation of NF-kB, says Dr Perricone. It also prevents the activation of collagen-digesting enzymes that are thought to be responsible for wrinkles.