Yes, but the other theory is this:
You can tell a lot about a person - including possibly their age - by what they think of when they hear the tune ’O sole mio.
For some people, the opera buffs, it's a Neopolitan Song written in 1898 by Giovanni Capuro and Eduardo di Capua. (And yes, I did have to look that up. So shoot me.)
For other people, those who were around in the 1960s, it's the Elvis song, It's Now or Never.
For still other people, the '70s generation, it's the Cornetto ad.
And if you really want to give your age away, you sing, "not bloody likely, it's 40p." Because seriously, Cornettos haven't been that cheap for ages. Probably not since they first started running those ads...
(This post brought to you by the fact that there always seems to be an ice cream van trundling around on our street playing that tune...)