If you ram-raid an ATM you are stupid or then again not. All the cash in it is DNA sprayed apparently, and will possibly lead an unavoidable path back to you.
Of course your perfect crime will depend on the willingness of society to fund the laboratories that will track you down and the legal parasites that will explore every possible way of getting you off.
DNA forensics is therefore both a symbol of Homo sapiens intellectual achievements and of our failure to understand how primitive we may always remain.
Our genetic 'code' doesn't begin to describe us, as your professor should know. All it does is perpetuate a lineage of primates.
I could murder my next-door neighbour later today and my legal team would tell me I was only guilty of having a 'psychotic episode'. I would be detained for a while in a suitably secure facility but my legal team would brief me, with the help of sympathetic psychiatrists, on how to persuade everyone I was no longer a threat to society and I'd soon be free.
DNA in other words is an enablement technology that cannot withstand exposure to that more significant perhaps non-DNA encoded aspect of humanity.
It, like all the incredible discoveries of science, cannot as yet withstand the two primordial traits of humanity namely greed and selfishness.