My sister says she has rotator cuff syndrome. Are family members more likely to get the same thing?

No. There is no definable family connection with rotator cuff syndrome. This shoulder problem is a result of many different factors, including the individual way that you are built and the way that you use your shoulder. I assume that there are similarities between the shoulders of sisters but it is not the extent that you have a greater risk than the anyone else. Although it is a common problem.
Not genetic. Rotator cuff syndrome is typically an inflammation in one of the tendons of the rotator cuff. It is often related to overuse with motion such as serving a tennis ball or throwing a baseball. Often it can be treated with rest, ice and nsaids. Strengthening of the rotator cuff muscles can also be done to help prevent re- currence in symptoms.
Yes likely. Although the exact genetic component has not been determined, people with relatives who have experienced rotator cuff tears are at increased risk of similar tendon tears themselves, according to a study published in the may 2009 issue of the journal of bone and joint surgery (jbjs). “this strongly suggests genetic predisposition as a possible cause for rotator cuff disease”.