Based on the lives of Australia's oldest citizens, the secrets to longevity have been uncovered and shared by Professor Robyn Richmond at the International Federation on Ageing conference, in Melbourne.

Alcohol drinking in moderation is fine says Prof Richmond but smoking is ruled out for longevity and it is also important to maintain a healthy and stable weight.

Even if you have one drink (a day) and drink within safe levels you're fine, said Prof Richmond from NSW University, who is the director of the Australian Centenarian Study.

Nearly half of them were moderate drinkers and 38 per cent did not consume alcohol at all.

She reported that none of the centenarians had risky alcohol use.

While positive outlook is vital, she says it also add years to your age if you are a female, as there are only 25 per cent of Australian men over 100.

Based on the study, Prof Richmond and his colleagues performed face-to-face interviews and took biometric measurements of 188 Australians of 100 years of age and over.

While, most talked of having relatives or siblings who lived up to the very old age, Prof Richmond said genes were only responsible for about 20 to 30 per cent of their longevity.

More powerful factors that contributed to their long life were a combination of diet, personal outlook, social and environmental factors.

She said, Even if you have got bad genes but you live a healthy life and stay positive, you could still have a very long life.

She said it is important to avoid isolation as about 88 per cent of the centenarians said they got together with their family at least once a week and 76 per cent joined routine group activities.

A total of 90 per cent were widowed or married and about 10 per cent were separated or divorced or had never married.

Sixty per cent of the centenarian still went for regular walks or remained active. None of them were obese and most notably, all reported having a stable and healthy weight.

She said when they recalled past behaviours, they noticed they experienced low neuroticism, low on fear, low on anger and were not hostile to others during their 30s to 50s.

They were high in extroversion and were conscientious, including dutifully following a doctor's advice, she said.

Prof Richmond said, the centenarians reported low levels of stress and anxiety and easily adapted to changes and did not internalize stressful events.

Australia has among the world's highest number of centenarians, and the figures have been doubling gradually every decade since 1981. The number is expected to rise up to 12,000 by 2020.