"Genomic analyses(3) show that SARS-CoV-2 is a chimera, with most of its sequence identical to that of the bat CoV RaTG13, except for the receptor binding domain (RBD), which is almost identical to that of a pangolin (Manis javanica) CoV and has been optimized to bind the ACE2 receptor in human cells.(3) Such gain-of-function chimeras can in principle arise via natural recombination, but that would be unlikely in this case. The natural recombination would require that the viruses from bat and pangolin infected the same cell in the same organism simultaneously, a rather improbable event considering the low population density of pangolins,"

The last line settles it -> "The natural recombination would require that the viruses from bat and pangolin infected the same cell in the same organism simultaneously, a rather improbable event considering the low population density of pangolins"