I'm not yet a mum but have a SIL who is banging on about her (admittedly v bright) child who is G&T. I've got mixed views about my own experiences although I don't think the label existed then in the same way.
Read fluently (reading age 11) and could do sums (junior level 3) at the first nursery class. Put up a year because teachers couldn't cope with the discrepancy in ability. Was happy enough at primary school (but recently re-read my school reports and was a bit shocked about the comments re my immaturity, and emotional difficulties - had I blocked them out in my memory?). Took 11+ at just 10 and went to grammar. Bullying was unrelenting until I got to sixth form when I was only marginally accepted because by then I'd stopped working. I cannot think about that school without crying even now. Was close to suicide a couple of times and v depressed for so long (not diagnosed until mid-twenties). Had no friends and hated being "different". I gave up working at school aged 12/13 - once you've come top of your year in every subject (ok second in music and RE) - where's the challenge? what's the point in trying hard if you are still going to get an A anyway? and anyway I was SO BORED by the lack of pace in the lessons... didn't work for Alevels (AABC) and did feel I'd let the side down by not getting straight As. Failed oxbridge interview due to lack of understanding what they were looking for (stage fright and first real experience of failure). Went to a good uni though and proceeded to drink, sleep around and act dumb in order to be more popular. Got a 2.1 without any effort. Felt bad for not getting a first. Fell apart in my early twenties. Only now, in my thirties do I feel emotionally resilient and together. I still struggle to make friends although I have strategies for appearing confident and sociable (nobody thinks I'm shy and my social awkwardness is not as extreme as it was). My few close friends tolerate my idiosyncracies and several of them are somewhat "different". I am successful in my career, have an MBA and am learning to not be embarrassed about being bright. When my IQ was last tested it was 159 so I'm no genius, but reasonably bright, I would say.
On the one hand it is important that children are stretched, whatever their ability, so that they can fulfil their potential and identifying the brightest and most able is one part of that. Otherwise it leads to boredom and dropping out. But being 2 years younger than your class mates (and physically slow to develop and with a mother who insisted I wear vests and knee high white socks until I was 14!!) is horrid. The loneliness, bullying and unrelenting nastiness of those years still haunts me.
Going back to my SIL - yes her child is bright - hardly a surprise because she and her husband are too. But I think her child would be happier in the long run if she accepted it, didn't fuss so much about it, and just concentrated on ensuring the child develops at their own pace, without the horrendous expectations and self-awareness of being so "special". That said, I know all parents do their best. My parents did what they thought best I accept that and no longer feel so bitter and resentful. The other posts from people on here are reassuring that I was not the only one to go through all this but it makes me sad too.