What can cause blood clots to happen to 3 generations of women in the same family? me 1st, then my grandmother who died from it, now my mom has one .

Clotting disorder: It appears that there us a clotting disorder in your family which has affected three generations. You have a hypercoaguable state which needs to be investigated by a hematologist.

Possible hereditary.: There are essentially 2 types of clotting disorders-acquired(not born with the problem but develops over time) and hereditary(passed on from generation to generation). Leiden factor v deficiency is a common hereditary deficiency that may not show up until later in life and especially around pregnancies. You should have a full coagulopathy evaluation by a hematologist.