How can hair loss/thinning hair be classified as genetic or medical/environmental? doctor says medications arent the cause, but research says differently. hair loss

Many possible causes: One's primary care doctor can check for medical causes. If none are found, then one can see a dermatologist, especially one specializing in hair restoration (some treatments: minoxidil, hair transplants,...). Medical causes may include: hormonal problems (low thyroid), seborrhea, alopecia areata, stressful illness. Other causes: genetic male/female pattern baldness, telogen effluvium, etc...