The Irish are actually 2nd in ginger percentage, behind my Scottish roots. Scotland is nearly 15% ginger, Ireland around 10%.
Oh, and both parents have to have the genes for a redheaded child to be born, but don't have to have red hair*. Also, red hair and blue eyes is shockingly rare, brown, hazel and green eyes is actually more common with gingers.
Oddly, redheads are more likely to have a low tolerance for pain (which I don't, I'm actually highly tolerant) and need more anesthetic to be put under (which I do). Weird.
FTR, my mom and dad both had dark brown hair, as did almost all of their siblings. Me and most of my 18 cousins have red or strawberry blond hair. Both of my grandmothers were gingers.
Lastly, my wife thinks this guy (Seaman Beaumont in Hunt for Red October) could be my twin. And my youngest son looks almost exactly like me.