DNA fingerprinting uses
restriction fragment length polymorphisms.
Compares and contrasts, even.
They are popular as paternity tests; half of your chromosomes come from your mother and half come from your fathers, so approximately half of the lines on your DNA fingerprint come from each parent, and no line in your DNA fingerprint lacks a counterpart in one of your parent's DNA fingerprints (barring the small chance of mutation - in the gametes or zygote, though if I was feeling really anal I'd qualify this statement - causing a restriction site(s) for the restriction enzyme used in the fingerprinting to appear/disappear). And if some of the lines on your DNA fingerprint are doubled/tripled/quadrupled up exactly then your parents are probably related.
Still not scientific enough. Phrase it again.