Final answer:
To establish that a child is related to both the mother and father, their DNA fingerprint must show similarities with both parents. If there are no matching DNA sequences between the alleged father and the child, then that alleged father can be definitively ruled out as the biological father.
Step-by-step explanation:
In order to establish that a child is related to both the mother and father, their DNA fingerprint must show similarities with both parents. DNA analysis can determine whether a man is the father of a child by comparing the child's DNA with the alleged father's DNA. If there are no matching DNA sequences between the alleged father and the child, then that alleged father can be definitively ruled out as the child's biological father.