I have had fibro all of my life and after I was dxed w/it in 2000 we found out that My Great-Grandma,her daughter,my mom and several other family members also too have fms but never knew what was going on w/them.I am a 4th generation fibro and i honestly believe that genetics has a lot to do w/this illness.
Some studies have shown a possible genetic link. There are so few studies on FM in general that's it's not well known. It also seems to run in families with other conditions such as ADD, depression. One person I respect researched and told me it also sometimes clusters in families with other autoimmunes like MS. So to answer you're question, it's very common to show up in families. It may not be genetic, it may be an environmental or in vitral link, or exposure to the same pre-disposing pathogen (that may or may not exist). I've ran several stories now saying "I swear looking back, my grandmother had, what I have, but it never got a name."
I can't think of anyone in Dallas off the top of my head. However, the www.cfids.org cfids association of america can tell you the local support groups, and they can tell you the local doctors for CFS. The national FM orgs can help with those support groups. If you get stuck, the head of the CFS NJ support group moved to Texas, so I'm sure the NJ group can give you the contact for a Texas support group. (NJ is a particularly large and active group, due to her work, and she travels up to help them regularly.)
Let us know how it's going... Good luck.