I suppose by "genetic evidence" for evolution is meant the DNA samples of different living species. So we find out that humans are 97% similar in their genotype to chimpanzees. And then I supposed they've gone on from there and shown man is related to other primates also, but not quite as closely. Then you could move from primates to whatever the next higher level is, and in all these cases you will find the genetic similarities gradually diminishing the further up you get taxonomically. I guess that's the way it works.
But what does this tell us? I think the idea is, if evolution is true, then the above scenario must be the case. The above scenario is in fact the case. It does not follow from this that evolution is necessarily true. What this DNA evidence does is eliminate a possible falsification.