Mary IS my Sister in Christ, and unfortunately, she can't chime in right now, you know why? 'Cause she's in heaven with EVERY other saint saying: "Thank you Jesus!!!" And if you're with Jesus, you certainly aren't worried about this...or anything else.
But on to my point: Adam's sin was imputed to all of His descendants, it had to be, otherwise the model of salvation suffers a fatal flaw: we can't all receive imputed holiness and communion with Christ otherwise. Paul is explicitly clear on this point.
Imputation is how one man's sin tainted the entire race; imputation is those in Christ are redeemed. Since Catholics believe that Jesus died for everyone, we have as series of flaws, each of them fatal. If Adam didn't impart sin to everyone, everyone doesn't need a savior, which makes Jesus and all His prophets liars. Let's not do that.
Or, if sin was not imputed to everyone (counter to what Paul tells us in INSPIRED SCRIPTURE), then grace is not necessarily imputed either, because..well, apparently, it just doesn't work like that.
No: the trespass occurred, however, the plan for redemption pre-existed Adam and Eve where as the devil planned the imputation of Adam's sins as a curse, God has used this to His glory and the salvation, sanctification and ultimately, the heavenly glorification of His saints, which is a better outcome than even Adam possessed before the the fall.