HI shania15,
There are alot of theories about how Rhuematoid Arthritis starts and develops, some Health Care proffessionals believe that it can be Hereditary, while other health care proffessionals believe that it can be enviromental, they have also been some research and claims, that some believe that RA can be triggered by an infection, or certain foods and allergies....
So basically what it all boils down to, there really isnt a clear answer to how and why RA can develop in some people, and not others, also based on research I did read a while back that they were trying to look into a study, that studies our Dna & physiology to see what makes our chromosones different from someone that doesnt have it... There is still alot to be learned, when it comes to RA..
Basically Ra, is an Autoimmune disease that is attacking our joints, & tendons and sometimes it can even attack our organs such as but not limited to organs like the heart, causing us to have inflammation surrounding the heart..
To break it down simpy, think about a person with a cold, our normal immune system builds up certain antibodies to kill off these types of infections & viruses, however when a person has RA, these antibodies also known as our immune system, builds up and tries to look for an infection that isnt there, soo becuase these antibodies can't find any foreign infection, these antibodies can't be released unless it attacks a foreign invader like an infection, soo therefore, our Immune system becomes our enemy, and attacks our joints, tendons and causes inflammation surrounding the joints, muscles, and tendons...This is the only way these abnormal antibodies also know as our immune system can be released, this is why many Doctors will prescribed medications that are in TNF Inhibitors category, to suppress our immune system, by suppressing our immune system, those antibodies that were in attack mode to our joints, muscles, and tendons are suppress, thus leaving us to a lesser flare up, and in the hopes of forcing a RA REMission....
who knows maybe its all of the above, maybe its enviromental, Hereditary and allergery base....and maybe depending on a persons personal body make up, you can have it or not...I do know that they are trying to develop more advance testing to decifer whether or not a person will develop this disease or not, regardless of family HX, allergies, and what ever other deciding factors, that are in involved...I hope this helps in answering you're question...and I hope i didnt talk ur ear off...LOL