Final answer:
The baby is not Sam's child if the baby's genetic fingerprint reveals bands not present in Sam's genetic profile. This method, DNA fingerprinting, is crucial in determining parental and forensic DNA matches.
Step-by-step explanation:
Sam is not the father if the baby's genetic fingerprint shows some bands not present in Sam's genetic fingerprint.
In DNA fingerprinting, which is used in paternity testing and criminal investigations, a child's DNA is compared to that of the potential father. If the child is biologically related to the man in question, all the genetic bands in the baby's DNA profile should have corresponding bands in the profiles of the biological parents. In other words, half of the child's DNA bands should match those of the mother, and the other half those of the father. Any genetic band in a child's DNA that is not found in the father’s genetic profile suggests that the man is not the biological father. This principle applies to forensic cases as well, where DNA from a crime scene is compared to that of a suspect to establish a match.