h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

i used to teach special kids.. was on the way to school.. for some strange reason i was htinking of this old rhyme 'ol mac donald had a farm'- was almost stumped when my brother, who was travelling with me, started humming this song- and i'm certaini wasnt humming it aloud. freaky. it s happened to us a couple of times!! any reasons? or are such things best left un-dissected!!!

It's been shown in experiments that closely related people, with a similar way of thinking, often have the same response to the same stimuli. You're probably a pair like that.
Plus when it's not a controlled experiment and you get to pick and choose what to consider important, it's not really that unimaginable that someone you spend a lot of time with occasionally think exactly the same as you.