I am a direct legacy (my mother) of Andover. Will this in any way affect my chances at other schools?
Well it may or may not. When I went to the Andover interview, she asked me why I was applying to Andover when my brother already attends Exeter, and I got the feeling that by telling the “second tier schools” that my brother goes to Exeter, they get the impression that they are simply backups to Exeter. I’m not sure about everyone else, but that’s just my experience
If, and this is a big if, it has an impact on your chances, it will be a negative impact for the reasons mentioned above.