One of the big problems was that ireland went to one potato variant, the lumper, which was the easiest to grow. When the blight hit, they no longer had a genetically diverse potato crop. If they did, they probably could have made it through much easier.
Yep. Another was that the blight wasn't restricted to Ireland but was throughout Europe, which meant that importing potatoes to offset the famine wasn't possible either. That's what the grain ships that were infamously taking grain from Ireland during the famine were trying to accomplish - the idea was that expensive grain could have bought much more inexpensive potatoes and fed more people than the grain would have. It would have worked, too, had potato prices on the Continent not also gone up in the meantime. As it was the ships kicked around port to port and really didn't accomplish very much. The grain would have been better off baked into bread.
Yup. There are 2,000 varieties in Peru where the 'Irish potato' originated. Most are resistant to the blight described.
I've heard that for many years.
In fact I've read that there was no genetic variation at all.
All the potatoes in Ireland were from a single potato plant.
In other words the potato blight was a disaster just waiting to happen.