I have IBS, my mum has it it too and possibly IBS-D since I suffer from diarrhoea. But I wondered if the diarrhoea could be from something else since my dad also suffers from diarrhoea but he doesn't have IBS.

Diarrhoea can be a feature of IBS or may be a stand-alone symptom that is due to something such as a food intolerance or food poisoning.

It sounds as if you have inherited digestive problems from both sides of your family and maybe working with a nutritional therapist would help you to discover the factors involved and format a plan to resolve them?