In the master's thesis we are dealing with the problem of genetic engineering. What are the ethical arguments of scholars, both those who are for the human genetic engineering training, and what are the arguments of scholars who are against such advancements. Throughout our work, the first part focuses on refinements, which extensively show us the problems of genetic engineering and the refinement of human nature. In the second part, we go to the specific technology CRISPR - Cas9, which could fulfill the desired human enhancements. Above all, ethical questions arise that touch upon the autonomy of man, his responsibility and, ultimately, his nature, the essence of human being. Later we focus on two topics that could result from CRISPR technology: created children and eternal youth. In the last third part, we focus on the Christian view of the subject. The view of Thomas Aquinas and his natural moral law is presented, as well as arguments for and against of various technologies that are or could affect humans (IVF, PGD, manipulation of the gene record). The main question is whether genetic engineering is something we should do. In conclusion, we can see that there is no easy answer. More than answers, there are many new questions that need to be answered or taken into our thinking before we actually allow the technology to be applied to humans.