Reductions in the cost of genetic testing and improvements in what we know about what it tells us produce obvious benefits; if you know you are likely to have some particular medical problem, you may be able to take precautions against it. But they also have at least one potential downside.
The more is known about the chance of bad things happening to us, the less able we will be to insure against them.
A solution to this problem that is sometimes proposed is to permit individuals to have their genes tested but forbid insurance companies to require testing as a condition of insurance or to use the information it produces. The problem with that is adverse selection. If the customer knows his risk and the insurance company doesn’t, high risk and low risk customers are charged the same price, making insurance a good deal for the former and a bad deal for the latter. Insurance companies, realizing that most of those who choose to buy their insurance are bad risks, will charge accordingly, driving more of the low or average risk customers out of the market. In the limiting case, insurance is bought only by high risk customers, at a high risk price. A famous description of the problem is Akerlof’s article “The Market for Lemons.”
If we allow both insurance companies and their customers to make use of genetic information, then both high risk and low risk customers can buy insurance, but at different prices. The risk of having genetic variants that make you more likely to suffer some expensive medical problem is uninsurable, although you can still insure against the risk that, given those genes, the problem will actually appear.







