Frame your argument a little differently - you're saying you can't be proud / ashamed of anything your parents have done (that you didn't contribute to).
Will you send a child to prison for crimes committed by their parents if the parents ended up dead by the time found guilty?
Human brains seem wired to have strong feelings about their kin or tribe. So, yes, I would think having neutral feelings about your parents would be a hard thing to understand for most people.