I think you missed the point. If neither the insurance company nor the insurance buyers have the relevant genetic information, then both are on an equal footing. If the buyers have genetic information but the insurance company does not, there will be self-selection (this already happens to a certain extent; if your ancestors lived to a ripe old age, you are less likely to buy life insurance). The people whose genetic information suggests they are at high risk of dying young will buy lots of life insurance, while those whose genetic information indicates a long life expectancy will not. In other words, genetic testing can be expected to change the composition of the buyer pool in the direction of higher risk, thereby changing the expected payouts.