You take the terrarum from the previous question and add sev…

You take the terrarum from the previous question and add several centipedes to the terrarium. The centipedes are display strong negative phototaxis and eat pillbugs. After several generations, you remove 20 pillbugs from the terrarium and test them to determine if they display positive or negative phototaxis.  Assuming that phototaxis in pillbugs is a genetically-controlled behavior, which of these is the most likely result?