« This story is not unique. In 2002, a woman learned that two of her sons were not genetically her children, but those of a twin sister who had never been born... It is now estimated that 8-10% of pregnancies are initially twin (and there are 1 to 2% of twins left), so there are many spontaneous abortions of twins and therefore potentially complex chimeras. »

« The assimilation of viral genes has occurred in the past. It would even be thanks to the fusion with a virus that Man would have differentiated himself from the great apes during evolution! It is a retrovirus, like AIDS. Retroviruses have the property of integrating their genetic heritage into the chromosomes of the host cell (in theory to be able to reproduce more easily). Researchers have not yet elucidated the function of these viral genes or by what mechanism they were able to allow the human species to move away from its primate cousins. The only known thing, and this has just been published, is that these viral genes present in human cells are expressed only during embryogenesis (the formation of the embryo from the fertilized egg) and then remain silent. So they certainly have a crucial function in an early stage of development. Researchers have discovered that 40 million years ago, another retrovirus assimilated by one of our primate ancestors allowed the formation of the placenta, an organ essential for reproduction. It is fascinating to think that without this virus, we might not have developed a placenta. Researchers have shown that a total of 8% of our DNA has a viral origin! »

« It is also known that many virus genes integrate into the genome of humans, forming mixed male/virus chromosomes. The HHV6 virus, for example, which causes a disease close to herpes, gives a spectacular illustration of this. In a number of cases, this virus integrates the woman's germ cells (the eggs used for sexual reproduction), which can then transmit not the virus itself but certain genes of this virus to her offspring. Whereas usually a child receives the genes of his parents and grandparents, the child here would have had a kind of grandfather virus! It would be a complete chimera since all its cells would contain a share of the genetic heritage of HHV6. This phenomenon is no exception. Viruses are permanently integrated into human and animal genomes. Depending on where the sequences are incorporated and other factors, the consequences will be more or less noticeable. »