I have just a small portion of Irish ancestry, but I think I’ve got the iron thingy.
It’s been mentioned to me several times that my blood tests show abnormally high concentration of iron and that’s one thing I have never supplemented.
Of course growing up just about everything I ate came from a cast iron skillet.
My siblings and I had well water with a high iron content for a substantial part of our younger years. Plus the iron pots and skillet!