You should check risk factors for blood clotting after your surgery by googling "Caprini score". With a family history of clotting, and a surgery over 45 minutes, those risk factors alone are sufficient that many surgeons (and most hematologists) would suggest that you will do well to have post op blood thinners (Lovenox injections) in addition to sequential compression devices during your surgery.
This is elective surgery and should be done in the safest possible manner.
If your father was evaluated for Leiden factor and has it you should be tested. If he wasn't tested, check with your primary physician.