So its simpler to assume that the Dragon Tear physically took DNA (when there is no indication that it effected DNA at all), than to assume that in the Chronoverse, souls have an imprint of DNA on them?
Who knows, does it is said somewhere in Cross about the latter?
All I find is about how they can be simulated to bypass death in Chronopolis, and Greco commenting how Serge's body and soul are different entities after him now having Lynx body.
Besides, that was in the case the soul doesn't contain imprinted DNA, to explain then how did HW's DT got it.