The range of human traits that have been studied is very broad. Genome specialists have looked for SNPs that are associated with:
- simple physical traits such as curly hair or attached earlobes
- complex social behaviors like reckless driving or marital infidelity
- medically relevant properties such as risk of breast cancer, prostate cancer, or diabetes
(Point to the image to show the complete figure.)
Some of these traits are purely genetic, but most are not. Take longevity, for example. Genetic background (i.e. the SNPs inherited from parents) is a key factor. But other things (diet, lifestyle, accidents, etc.) also affect longevity. Genomics cannot predict an individual's life span, but it can identify those more likely than average to live long.
Likewise for complex diseases. Genomics cannot predict who will or will not get sick, but it can reveal important relative risks.
The answer to all of these questions is yes. The reliability, validity, and usefulness of studies like this can be very high, provided they are performed and applied properly.
The quality of genomic data depends on many factors, such as the sizes of the study groups and their composition. These technical issues are beyond the scope of this web site, but they are examined carefully by the scientists who perform and evaluate these studies.
Physicians use many tools to help patients avoid chronic diseases. These range from simple dietary advice to invasive steps including medications, procedures, and even surgeries. All of these steps carry risks.
Genomics helps us find the people for whom these measures are most likely to be benficial and least likely to cause harm. In doing so, genomics can help keep the population at large healthier while also reducing medical costs substantially.