Recently a friend asked me what advice I’d give my younger self. The reply I gave was deliberately glib: get a fringe, relax with the eyebrow pomade, don’t shag X because you’ll soon realise he’s mean and ugly. In reality, the lessons I’d tell my younger self are very different. I won’t share them here because they’re much more serious than the ones I gave my friend over WhatsApp. They’re serious because I think about them all the time; and I think about them all the time because I am continually confronted with the spectre of that younger self via the dubious magic of social media.

I’ve been thinking about this more recently – perhaps because I am getting older and my life is changing, yet I still feel a baby emotionally speaking, so both these things terrify me – how having constant access to social media complicates our identity. The question “who am I?” has always been impossible to answer (if Socrates couldn’t figure it out, I’m definitely not going to), but it feels increasingly difficult in the digital age because we’re always being exposed to our past selves. Even as a nostalgic person, I had to delete the Timehop app because it kept serving memories of who I used to be, making me spiral into wondering: Am I happier now? Am I a better person? Am I, perhaps more crucially, hotter?

The early days of social media, which coincided unhappily with my adolescence, were overwhelming because suddenly we had unprecedented access to a constant stream of beautiful, successful strangers, served to us by the algorithm. As a teenager these were the people I compared myself to and mentally competed with. As an adult, I compete instead with strange, doppelganger versions of myself. I can, if I want, scroll ad nauseam through all my previous lives, the ones that litter the internet because nothing can ever properly be deleted. Old boyfriends, old bad eyebrows, friends I no longer speak to, vintage jackets I lost somewhere among my many house-shares, which I am still furious about.

I sometimes forget that my online persona is what people expect when they first meet me

My identity has changed so much since I first logged on that this past me is almost unrecognisable (at least to myself). The weirdness of this is something I think is specific to millennials. Gen Z (and coming up close behind them, Gen Alpha, the grown-up iPad babies) have always been online. Their parents have the good sense to shield their faces from the feed until they’re old enough to understand and consent to post themselves. They’re savvier than millennials, who would happily go out with digital cameras and upload MySpace albums of 700 photos from a students’ union bar. Boomers and Gen X have the luxury of most of their misspent youth being offline and easier to forget. It’s millennials who constantly have to face up to Facebook memories of them wearing YOLO leggings and bumpits, millennials who have to confront Instagram views of the “talking stages” that failed to turn into relationships, even though they’re now married with kids.

I sometimes forget how much I’ve changed until confronted with the bumpit throwback pics, which is useful in a way. Since joining Instagram I’ve moved countries several times. I’ve posted (shamelessly) about every relationship I’ve had and left clues for people to work out when they end (but no more boyfriend on grid). I’ve posted about chronic illness and money and work and jobs and going to Fashion Week. I sometimes forget that the adult persona I’ve created online is what people expect when they first meet me for real. Recently I scandalised someone I didn’t know well by referring to myself as a “chav”. I thought I was poking fun at myself and my aesthetic (“chavcore”) but it landed badly because the person I was speaking to knew me primarily through social media. They had never scrolled back – why would they – so didn’t know me before I became an adult in a Burberry shirt. I still consider myself working class (and the shirt was second-hand off eBay) but I’m forced to admit that identities change. People read my current identity, through the conduit of the feed, as middle class. So my joke didn’t come across as self-deprecating, just tone-deaf, callous and classist. It made me wonder if I should be changing my offline self to fit the online one, and if the identifiers I use have become less authentic over time. Can I still call myself Irish, and post all the time about Irishness, if I haven’t lived solely in Ireland for almost a decade?

I know deep down that I’m not the person in my Instagram captions or snipey tweets, it’s just that it’s increasingly hard to separate that online identity from my own. Harder still to decide which is better, or worse. I do worry about how constant access to our past selves impacts on our sense of who we are in the present. We know, obviously, that identity and growth are not linear. The problem is that our timelines are.

Róisín Lanigan is a writer and editor based in Belfast and London