<<Disclaimer: Verify this information before applying it to your situation.>> Sorry it took a while to summarize! It seems that the medical opinion most cited for celiacs having celiacs is around 10% occurence. (In my question, I had thought it was higher).This figure comes partly from the most recent studies of the Center for Celiac Research. They are doing Multi-Center serological screenings to determine the prevalence of Celiac Disease int the US. and part of this is with 1st and 2nd degree relatives. Preliminary results show: 1st degree relatives of celiacs - 1 out of 12 2nd degree relatives of celiacs - 1 out of 11 (This figure is on testing 1,819 first degree relatives and 352 second degree relatives. This is preliminary data - they will be testing many, many more people.) For further info on the Center for Celiac Research and this study, see: http://www.celiaccenter.org/frm_research_update.htm Seven other people responded also that 10% is the percentage most agreed upon by rest of the medical community. Quite a few people commented that ithey think the percentage is really higher from comments made on this list, but maybe that is because people who are celiac themselves might comment about their children if they are celiac, but don't mention their children if they are not. One lady responded that she was celiac and that none of her three children or 10 grandchildren were celiac. Anyway, hats off to Dr. Fasano and all those helping him for their hard work and dedication with the above study. Let's support this research by donating what we can through our support groups and individually! The above site gives details. (I have no financial interest in this of course - just celiac interest!) Thanks to everyone for responding!! Linda in Mississippi