I'll be surprised if we're that uncommon, puffyprue. My cousin is 6 yrs older than me. He had his own name for me and biked from a Chicago suburb to spend time with me when he was amid. I adored him, all the more as I grew up. My family moved to FL, but we remained close.
There wasn't ever any romantic stuff between us, but an airport visit as I changed planes was sufficient to cause his fiancée to break their engagement. Still don't get that. More had to be going on with them.
The woman he eventually married was a needy, jealous sort and we never spoke together again after they met.