My stepmom used to be amazed (and a bit annoyed) at how I was always humming or singing a line from a song, in apparently random succession, because I was always being reminded of songs by the things she was saying. She's gotten used to it now ...

I think I got the tendency to sing through my days from my mom. She knows the first line (only) of "every song ever written" and I have picked these up from her. I think my husband was also somewhat frustrated with my tendency to sing little snippets of songs all the time, often inventing lyrics to fill in what I didn't know, but he's now accustomed to it. (I keep telling him - if he wanted a normal wife, I was the wrong choice - and he knew what he was getting himself into! )