"We are the first generation in human history to have access to our own genetic information; who can change our ways of seeing health," says Kwok, medical director of LeGene, a private clinic offering genetic services.

Besides determining more superficial physical traits such as hair and eye colour, the information stored in our genetic database and unlocked through clinics like Kwok's can reveal the risk of developing diseases (for example, the mutated BRCA1/2 genes associated with breast cancer) and the underlying causes of mysterious health problems. The tests are now even being used as indicators of a child's aptitude for sport or which subjects he or she will do well in at school.

"It's totally different from the old way of checking health," Kwok says. "Back then, you could do scans, you could do blood tests and so on to see if anything existed, but only on that day. So if you scanned one day but your cancer started growing the next, you wouldn't find anything.

"That's the gap that's filled by genetic science. We're not testing [to find out] if there's anything wrong today, but if there's anything wrong with your operation manual from day one, that will go on until the end of your life."

The cost of sequencing a person's genome has plunged from US$3 billion (the amount spent on the Human Genome Project) 13 years ago to about US$1,000. As a result, gene testing has become something of a boom industry. It took hold first in the US, and has since sparked concerns over people's easy access to information they don't really understand. But regulations are now in place to ensure the involvement of doctors throughout the process. Earlier this year US President Barack Obama pledged that the 2016 budget will include US$215 million for so-called precision medicine, based largely on genetic testing.

The tests were also applied in Saudi Arabia where, according to local reports, 165,000 couples broke off engagements in one year when government-mandated genetic tests found them to be at risk of passing on hereditary conditions if they had children.

As gene testing becomes cheaper and quicker, a slew of companies have emerged in Hong Kong in recent years to provide such services, among them Dr Gene, DNA Laboratory and Gene Track.

At LeGene, packages start at about HK$2,800 and reach HK$180,000, including full support counselling and services. Kwok estimates the clinic sees about 100 clients every month.

The process is fairly straightforward. Clients provide a saliva sample, which is stabilised in a special chemical solution before being sent to labs either in Germany or the US, depending on the expertise required.

The results, once analysed by a trained geneticist, give patients a snapshot of their genetic code, including "spelling mistakes" which can give rise to different illnesses.

Increasingly, tests are being offered that claim to predict children's aptitudes in particular areas; for example, the ACTN3 gene, which has been associated with elite athletic performance, is being used as an indicator of sporting talent.

Joe Yu Men-yi, a 38-year-old mother of three, recently used LeGene to examine the DNA of her seven-year-old daughter, Jamie, to find out what talents she would have.

"We found out that she doesn't have the genes for sports and muscle growth," Yu says, "so we're not pushing her to do sports or play musical instruments, which require precise muscle movements."

She says the results also showed Jamie was genetically predisposed to struggle with English compared to Chinese, which is why she plans to focus her daughter accordingly.

Yu explains: "This makes parenting much easier, knowing the strengths and weaknesses, and not wasting time, money and other resources on things that aren't necessary to a child's education.

"In Hong Kong, parenting focuses mostly on academic subjects and everyone is trying to do the best for their children. Doing this [test] means we know what's best for the child, so we can win at the starting line."

According to Kwok, because Chinese characters are pictorial-based, they are processed in a different part of the brain to that used for English, which is letter-based. So if one part is going to be stronger than the other, you'd have a greater natural ability with one language over the other.

For Kristy Wong Tsz-wun, 28, a genetic test helped make sense of some inexplicable rashes and her extreme lethargy, which seemed excessive even if she considers herself "very fat".

The results indicated she had an intolerance to eggs and bread, which were causing the rashes, upsetting her digestive system and affecting her energy levels. Now, Wong steers clear of both foods, exercises daily and is trying to use what she has learned to lose weight and stay healthy.

Perhaps more worryingly, the test suggested she was 40 per cent more likely than the average woman to develop breast or ovarian cancer.

"I gave my results to my family doctor so he could come up with a schedule for me to get screened for the cancers. The test results are a very good reference."

But as demand grows to inspect our genetic blueprints, experts caution people against reading too much into the findings, which indicate probabilities rather than certainties.

Last week, the American Society of Human Genetics also issued a paper warning against genome-wide testing unless clinically indicated, especially for children.

Advances in genome sequencing, chromosomal analysis and direct-to-consumer testing now offer the public easier access to personal health-related information. But the association says this data is largely about probability, and the tendency towards making genetic prediction might create a dark cloud that changes how the family and others think about a child.

And with athletic performance influenced by a complex mixture of factors, from individual passion and their environment to the interplay between as many as 200 genes, scientists argue it would be simplistic to think that the presence of one or two genes might mean a future Serena Williams in the family.

At the University of Hong Kong, clinical geneticist Dr Brian Chung Hon-yin notes that genetic factors contribute only partly to a person's development; nurture often wins over nature.

That's why Chung and his colleagues are training doctors and nurses to talk patients and clients through the science of such tests, the possibilities that the results present, and what they can do next.

"Genetic tests are very different from the other tests that we can offer in clinics or hospitals. It has to be packaged with adequate counselling before and after the tests. The key is to help the client adapt," Chung says.

"The adaptation is not just medical. What do you tell your parents, your family? What about your expectations for your child? You once expected him to go to the University of Hong Kong, but now you'd be happy if he can just live an independent life. You have to help the parents or families to go through this."

Of late, he has been pressing to create a university programme for genetic counsellors and last month organised an international conference at the university which addressed, among other topics, genetic counselling.

Co-organiser Dr Olga Zayts says one problem is doctors who are not trained in counselling tend to forget that patients have to make their own choices based on the information presented.

"Medics in general aren't aware how directive they are. They're trained to tell people what to do, and they continue doing it with counselling as well.

"This leads to doctors simply telling the patient, 'We've got your test results back, I'm going to take a needle to puncture your tummy'. But the course of action may not be one that the patient wants, and many doctors are not even aware that they are issuing directives rather than helping people make choices," Zayts says. "You have to explain the test results."

There is clearly a need for counselling training in the public health system; Yoyo Chu Wing-yiu is the sole qualified genetic counsellor serving public hospitals.

Clinical genetics is still under-recognised in Hong Kong, which explains the lack of specialists, says Chu. She trained in Australia, where the profession is more developed.

At the LeGene clinic, Kwok reckons genetic services in Hong Kong are about 10 years behind the US. His clinic must still send samples for testing at laboratories abroad because of the lack of accredited local facilities

Still, he is hopeful that the fields of genetic testing and counselling in Hong Kong will grow over time.

"We are talking about lives. We aren't talking about the latest mobile phone. We are talking about living longer, and healthier, without disease."