Earth’s abiogenesis could have started via a cosmic payload as well, which potentially answers your question regarding the shared biochemistry. [0] https://en.

Earth’s abiogenesis could have started via a cosmic payload as well, which potentially answers your question regarding the shared biochemistry. [0] https://en.m.wikipedia.org/wiki/Panspermia https://en.m.wikipedia.org/wiki/Panspermia