Just 'cos you don't have any family with IBD doesn't mean you can't have the genes for it. Genes skip generations or else lie dormant and are never activated. My mum passed on the genes for Crohn's to me but doesn't have it herself - whether or not she
could get Crohn's is an unknown quantity.
If there is literally no genetic basis for IBD, then it's hard to see what else it could be other than an infection or lifestyle disease. I don't agree with the latter, 'cos virtually everyone in the western world suffers from stress - why don't they all get IBD? If anything, the UC population seem to be healthier than the general population, although I'm basing it on an unscientific hunch rather than solid evidence.
Edit: There are loads of genes associated with IBD. Interesting diagram here:
www.ibdresearch.co.uk/what-is-inflammatory-bowel-disease-ibd/identifying-the-ibd-genes/Post Edited (NiceCupOfTea) : 9/19/2016 10:18:27 AM (GMT-6)