Genetic prediction is at the cross road of the various meanings of the concept of personalized medicine or medicine 4P: Personalized, Preventive, predictive and participative, also called precision medicine or prevision medicine. This entire frame questions i) the place of data in medicine and its consequences on the relation between patients and doctors; ii) the empowerment of people in the management of their own health; iii) the access to health related data outside the health system (tests directly provided to the consumer over the counter). These various dimensions are analyzed through the phenomenon of massive data and large-scale genetic tests, in particular DNA sequencing in the clinical frame, the blurred limits between categories previously clearly distinct (e.g. research versus clinical care), the recommendations of professional societies of human genetics. The analysis conducted shows that the technological development and the tools of personalized medicine cannot occur in a responsible way without a concomitant analysis of the underlying values at stake.