Over 50% of non-celiac wheat sensitivity (NCWS) patients are HLA DQ2/DQ8 positive and often have a Celiac Disease (CD) family history. Studies have identified a subgroup of NCWS patients whose clinical and immunological features are closer to CD than to irritable bowel syndrome/functional dyspepsia (IBS/FD) ('inflammatory subgroup'). The investigators hypothesized that among CD patient's relatives, there might be a high number of NCWS subjects, who hypothetically belong to the 'inflammatory subgroup'. Therefore, the aim of this multi-step project is to identify the prevalence of both self-reported NCWS and IBS/FD not related to wheat ingestion among CD patient's relatives (parents, grandparents, siblings and sons).