A complex interplay between genetic susceptibility, environmental factors and clinical indicators seem to cause the development of Crohn’s disease (CD). Few disorders in clinical medicine are associated with as much chronic morbidity as CD. Genetic factors are the predetermined cause, whereas non-genetic factors seem to further trigger the development of CD. From epidemiological data, based on concordance statistics in family studies, via linkage analysis to Genome Wide Association Studies (GWAS) and Whole Genome Analysis (WGA), robust evidence have been gathered, implicating distinct genomic loci involved in genetic susceptibility to CD. Most recently, a meta-analysis has been able to implicate 71 distinct genomic loci that seem to be associated with CD development. A study published in the American Journal of Human Genetics has also recently identified more than 200 genes associated with CD, which is more than what have been found for any other disease so far. Monozygotic twins show approximately 50-60% disease concordance, with much lower rates in dizygotic twins (~10%), highlighting the role of both environmental and genetic components in the development of CD.