This woman is an adult, she obvously doesn't have Marfans, she would have known by now. If you do not have a genetic history because of adoption then it should be the job of first the adoptive parents to get full tests to make sure there are no pressing medical issues, then it should be the job of the adoptee to continue regular screenings and making sure they keep themselves at a healthy weight with healthy habits just as if someone knew they had a predisposition to something.

The best thing they can do is before they have kids to make sure they and their partner get a full genetic work up to make sure they both don't carry Tay Sachs or Sickle Cell or something equally awful.