Under the expected utility hypothesis a costless genetic test has, at worst, zero private value. This happens if it does not affect optimal decisions. If the genetic test facilitates better decision-making for at least one possible test outcome, then it has positive private value. This theoretical result seems to contradict the fact that empirically observed take-up rates for genetic tests are surprisingly low. We demonstrate that if individuals display ambiguity aversion, a costless genetic test that does not affect optimal decisions is never taken. Furthermore, there is a trade-off between aversion against uncertainty of test results and utility gains from better decision-making if optimal decisions depend on the level of information. The reason is that, from an ex-ante view, a genetic test introduces uncertainty of probabilities which diminishes the value of information to an ambiguity-averse decision-maker. Ambiguity aversion regarding test results thus provides an explanation for low take-up rates for genetic tests. Copyright Springer Science+Business Media New York 2014
