Having compatible DNA is very unlikely, just about the only way it could happen is if you had some form of cross contamination, like a panspermia event. Just having DNA may not be hard but have a compatible sequence (same nucleotides and codons) is just too unlikely to be believable without a common ancestor.

Having compatible DNA is very unlikely, just about the only way it could happen is if you had some form of cross contamination, like a panspermia event. Just having DNA may not be hard but have a compatible sequence (same nucleotides and/or codons) is just too unlikely to be believable without a common ancestor.