Once upon a time, pop/rock/alternative music consumption was strictly for teenagers; you got into it when the adolescence hormones hit your bloodstream and you needed something that was yours and not your parents', spent a few years spending your pocket money on 7" records and dressing in a way your grown-up self might later find as embarrassing as your parents did at the time, and dropped it just as quickly when you Grew Up, got a job, married and had kids of your own and were saddled with the burden of adult responsibilities which you would carry unto the grave. Gradually the boundaries got pushed back, and a whole market of “adult-oriented rock” emerged; engineered to soothe the nerves of stressed Responsible Adults whilst providing them with just enough of a hit of what excited their younger selves a quarter-century earlier, it tended to a sort of soaring, platitudinal blandness; a weak substitute for what had been forfeited. Though over the past few decades, the idea that one must check one's musical/subcultural identity at the door of adulthood has been eroded even further. The pioneers may well have been the Goths, who stubbornly refused to Grow Out Of It well into middle age and beyond; though soon, the commodification of cool into cultural capital opened the doors further, until soon we had shops in trendy areas selling Ramones baby clothes and lullaby renditions of The Cure and Nirvana, and bands classified, back-handedly, as “dad-rock” or “dad-house”. This isn't completely universal—after all, supermarkets flog millions of records by the likes of Coldplay and Ed Sheeran for people who either never were into music or else vaguely remember what it felt like but have no desire to regress to that phase of their lives—but one no longer has to be a fringe-dwelling bohemian to remain particular about music
Of all the genres and subcultures, though, the indiepop scene seems to have become uniquely small-child-inclusive. As a critical mass of indiepop kids hit middle age and have kids of their own, they are more likely to bring them, en masse, to gigs and festivals, and adapt the events themselves for the kids; songs with rude words are dropped or bowdlerised, balloons are provided, and the gig becomes a mass playdate first, and a musical performance only tangentially to this. Flocks of toddlers run around, yelping and shouting gleefully, and it is seen to be their right to do so; anybody who objects to this getting in the way of their enjoyment of the music may as well be a fascist or a Tory or something equally unspeakable. The music's almost just a side product for the parents' benefit. Elsewhere, there are indiepop baby discos, acclimatising young ears to Belle & Sebastian and Allo Darlin' from an early age. Perhaps, elsewhere, there are pint-sized punks pogoing anarchically to toddler-friendly renditions of Anarchy In The UK, baby discos spinning gnarly brostep, or black-clad toddlers running around like swarms of ground-hugging bats at the Whitby Gothic Weekend, but such possibilities notwithstanding, this seems to be peculiar to indiepop. There are no boisterous toddlers at, say, shoegaze, psych or post-rock gigs; other festivals may have a few small children in attendance, but they are fewer in number, and where special provision has been made for them, it is away from the stages.
Why indiepop has, upon its members' parenthood, shifted wholesale into a toddler-friendly environment is not certain. Perhaps it's a natural outgrowth of the “twee” signifier, which originated in the 1980s as a rejection of the hypermasculinity of hardcore and/or post-punk rock, instead embracing, with varying degrees of irony, the signifiers of childhood. Much in the way that things that start as ironic appropriations often end up shedding the irony and continuing with some degree of sincerity (as seen, for example, with the “ironic” sexism of 1990s “lad” magazines), a scene whose zines and button badges copied old children's books might transform from a subculture questioning the inherent conservatism in the childish/mature dichotomy to a subculture tailor-made for small children and their parents.
It'll be interesting to see whether the toddlerification of indiepop changes the subject matter of it more than removing the word “fuck” from lyrics. Thematically, indiepop songs do tend to hover around adolescence and its long decay envelope, with themes of crushes, break-ups and being in or out of love cropping up disproportionately often. These days, this is even more so than in, say, the C86 days, as “twee” became stylised and codified into a somewhat excessively fey, cupcakey aesthetic, and some of the oddness of 1980s-vintage indie has been replaced by chaste adolescent romance like a plot from an Archie comic soundtracked by vintage Motown girl groups. Perhaps as the under-5 demographic at indiepop gigs swells, these themes will be displaced to some extent by songs about dinosaurs, monkeys, pirates, rocket ships, monkeys who are rocket-ship pirates, poop and other things more likely to appeal to actual small children.
Secondly, it will be interesting to see what a generation of kids who were brought up listening to twee pop from birth end up doing when adolescence, and the need to individuate themselves, hits them.