I'm the firstborn. I don't get cluster headaches, though.
However - among my siblings, "Firstborn" means "born in 1939, remembers Dad going overseas and remembers him coming back - remembers rationing and blackouts and brown sugar sandwiches and the coal stove - " and second child means "Born in 1941 and tiny when the family moved back to Grandma's block because Dad was overseas. Lastborn means "Boomer and Male - if he weren't such a sweetheart it would have been easy to be jealous. And now he's a sober greybeard!
Pat, creaking relic from the last cycle of history.