The possible remains of King Richard III of England have recently been discovered. His identity has been confirmed by DNA PCR analysis. Descendants of his mother in the female line have the same mitochondrial DNA as King Richard. However, the results with the Y chromosome were surprising. None of the descendants in the all-male lineage had the same Y chromosome markers as King Richard. This is almost certainly due to something called a "false-paternity" event. (There are other ways of describing this event.) Given what you know about PCR, what are some possible sources of error in this analysis? Would you be prepared to go back in time and accuse one of the Kings of England of being a bastard? [Identification of the remains of King Richard III](The lab experiment was to analyze various foods to see if they were made from genetically modified plants.)
Note: It's extremely unlikely that the "false-paternity" event occurred in the lineage leading directly to any of the Kings and Queens of England.