DD and DS1 have both had it. DS2 has been exposed to it many, many times but still has not contracted. CP. Whilst I would not send him to a CP party or anything like that, I really wish that he'd had it over and done with by now. He is 6 and a girl in his class and her sister who are our neighbours have both just had it and been in school whilst contagious in a close up and cuddly Reception/Y1 class.
I recall my father getting CP when I did aged about 7 and he was VERY ill. It is my understanding that as an adult it can be pretty bad and so it would, I presume, be A Good Thing for him to get it in childhoood, yes?