Mom had blood clot after knee surgery 5 yrs ago. Meds helped and she now has no clots. I am now pregnant at 37 y/o am I at risk for blood clots now too because she developed one after surgery? I've read it runs in families but she never had it prior.

Genetic test. It is not likely that you are at more risk than other pregnant women. There are genetic tests for variants of factor II and V that can be ordered by your doctor. You should have a talk with your obstetrician to ascertain if testing is warranted.
Wish you good health and a healthy baby!