I remember a long time ago, when my son came out of school (we live near Manchester) and he said that he wanted to be a Man U supporter.
I apologised to him for not making the situation clear, told him when we got home we had better pack his bag as he was not living under my roof unless he supported Everton. He said he could not argue properly with the Mancs as they were winning everything, I told him those two little magic words to use to any supporter of a different team - you know the ones, short sentence, two words, three fs - he soon got the message and grew up to choose uni in Liverpool so he could get a season ticket and follow the team properly.
My son, a good 'un. My parental skills exceptional!