Knee pain may be due to early onset of degenerative arthritis, just mother having RA doesnt have to follow into you. If you have symptoms of difficulty in bending fingers or making fist in early hours of morning, hand joint pains, then you should get checked via lab investigations.
Next Steps
Physiotherapy to strengthen knee joints will be of help, consult orthopaedician, get a xray done and blood investigations done to rule out RA. So you can take treatment in right direction