What's the longest-lasting grudge you've held against a house guest, and what did they do to deserve it?

Why do intelligent people often reach completely different conclusions after looking at the same evidence? Is the difference in the facts or in the way our minds interpret them?
How does the constant need to hide a private struggle change the way a person observes their surroundings?
Do you really think that I should put your ideals ahead of my own family members?