I don't think it's childhood related. On the contrary I think it's partly generational - when I was a teenager in the 80s I remember everyone in my peer group and the magazines we read saying that drinking a lot of water was key to a clear skin, long before other benefits were much discussed, and I took up drinking lots of water and my mother constantly questioned this and assumed at least once per month that it meant I was ill! To be fair my skin has always been reasonably clear 😜
I think a compulsion to drink every few minutes developed in the last decade when people misinterpreted/ massively exaggerated the need for hydration in order to concentrate at school. Of course hydration is essential but it was carried way out of proportion to mean nobody should go even a few minutes without access to a drink, leading to children (teens especially) insisting on their right to drink constantly at school throughout lessons, debates on children being allowed soft drinks instead of water because of the ridiculous claims that certain children "couldn't" drink water (but somehow could drink ribena / squash or Fanta or orange juice) ... then of course all sorts of commercial interests pitched in selling "flavoured water", "sports water" etc partly because sales of sugary drinks reduced somewhat as people started trying to avoid so much sugar, and the industry needed to plug the revenue gap...
My mother thinks having had a cup of coffee at 8am with breakfast means someone couldn't possibly be dehydrated at 2pm, but I drink half liter/ pint glasses of water with meals and whenever I sit down (which to be fair isn't a lot because my work is not desk based and I'm out a lot in my free time, but I drink at least 3 liters of tap water per day, and my parents never drink tap water at all and never have).
My biggest bugbear is people who insist they can't drink good quality tap water, and expect bought bottled water - which especially if contained in plastic is generally worse quality than the tap water where I live.
Like most things actually the middle ground is the right place for most people - drink enough but don't get stressed at going an hour or three without drinking, that will do absolutely no harm at all if you were properly hydrated at the start - after all nobody drinks in their sleep!