Rhiannon Harries: Who's that poking their nose into others' business? Oh, it's me...

Alter egos can be exciting, unsettling things. Many of us secretly like to believe that, deep within us, there exists an alternative self, unconstrained by social and moral obligations. It's the person we might be – and, in occasional spontaneous moments, that we are – if we were completely free.

As a rule, a second persona is the subversive, perhaps even frightening, but ultimately far more intriguing counter-point to our responsible, day-to-day selves. Although not, apparently, in my case; I don't know when or why it happened, but at some stage in the past 12 months my alter ego has started to resemble a matronly schoolteacher of yesteryear.

I should clarify that in ordinary life I am a fair way off qualifying as a Hunter S Thompson type, yet I have always viewed a minor irresponsibility here and there through a filter of romantic charm. That's why it has been with some astonishment that I have found myself given to involuntary outbursts of civic responsibility of late.

A mid-morning trip to the corner shop last week provided the best instance yet. I was barely aware of having registered the two preteen boys in school uniform ahead of me before an unknown voice trilled, "No school today then, boys?" It was only when one turned to mumble, "Er, we're on a free period!" (obviously a lie) that I realised, horrified, that the teacher-style phrasing and shrill tone belonged to me.

Things have been heading this way for a while, but so far my cowardice has at least kept this nascent busybody in check. I have hitherto restricted myself to glaring at people who put their feet on the seats on public transport until they actually return eye contact, or tutting at queue-jumpers before remembering that it wasn't long ago I considered it an Olympic sport.

On the one hand I'm pretty aghast at this side of my personality, particularly since it has been accompanied by an equally novel affection for early nights. But on the other hand, I'd like to think it offers a little hope at a time when civic values seem to be in such scarily short supply.

Police inaction has been widely blamed as a factor in Fiona Pilkington's decision to take her and her daughter's lives after years of horrendous bullying by local youths, but the situation might never have arisen if kids grew up in a society where everyone – and not just their alter egos – had the confidence to reprimand bad behaviour.

I can't claim that any of my low-level reprimands have yet made a difference to the state of the nation, but I'm learning to embrace my inner meddler. It's not cool, it's not sexy, but for me, it's really quite radical.