also known as

DNA Fingerprinting

Superman is married to Lois Lane and they have a young son named Johnny. Lately Superman has begun something is amiss with Johnny because he can find his way in the dark and he has a tendency to hang upside down from light fixtures or dark corners of the ceiling. Superman begins to suspect that Lois may have had a fling with her old boyfriend, Batman.

Superman gets a court order for a blood sample from himself, Lois, Batman and Johnny. The DNA in each blood sample is amplified (increased is quantity via PCR). The DNA in each blood sample is then cut using restriction enzymes and the DNA fragments are placed in separate chambers of a sheet of gel in an electrophoresis chamber. After an electrical current has been run through the gel, you, the famous paternity judge, view the evidence on the electrophoresis gel (See diagram below.). Who is the father of Johnny?

The fragments on Johnny's profile should be a mixture of the profiles of his 2 parents. It should be fairly evident that the fragments or lines for Lois and Batman are most similar to those of Johnny. The profile for Superman is not very similar to that of Johnny. Thus, Batman is most likely Johonny's biological father!