If the future were knowable, would we want to know it? When I was young, a fortune teller who predicted several things in my life that subsequently came true predicted my age at death. At the time it seemed an eternity away, so I thought no more of it, but now it is not so very long away at all. If I were more disposed to believe the fortune teller’s prediction than I am, would I use my remaining years more productively or would I be paralyzed with fear?
In a recent edition of the New England Journal of Medicine a question was posed about a 45-year-old man in perfect health (insofar as health can ever be described as perfect) who asked for genetic testing about his susceptibility to cancer, given a fairly strong family history of it. Should he have his genome sequenced?
A geneticist answered that he should not: to have his entire genome sequenced would lead to a great deal of irrelevant and possibly misleading information. But if the family history were of cancers that themselves were of the partially inherited type – more factors than genetics are involved in the development of most cancers – then the man might well consider having the relevant part of his genome, namely that part with a known predisposing connection to the cancers from which his family had suffered, sequenced.
This is not a complete answer, however. Two obvious questions arise: is additional risk clinically as well as statistically significant, and if the risk is known can anything practicable and tolerable be done to reduce it? There is no point in avoiding a risk if to do so makes your life a misery in other respects. You can avoid the risk altogether of a road traffic accident or being mugged on the street by never leaving your house, but few people would recommend such drastic avoidance.