Until recently there has been a wide consensus among bioethicists about ethical demarcation line between somatic and germ-line gene interventions. From the end of the 1990s this demarcation line has started to be undermined. Recently, mitochondrial replacement techniques which cross this borderline have been legalized in Britain. In addition, new very precise gene-editing techniques CRISPR/Cat9 have already been applied in experiments on human embryos. In reaction, some scientists in a letter to the journal Nature call for moratorium on human germ-line experiments. The aim of this paper is to reconsider in the light of recent scientific achievements concerning the complexity of human genome two frequently used arguments against inheritable genetic modifications: that of a high risk of destroying human genome and that of the necessity to protect human nature.