My son was definitely talking in full sentences when I went to Uni when he was 13 months old (the youngest age the crèche would accept). His first word at 9 months was the rather glorious ‘bollocks’ (he was out with his Dad & a guy next to them tripped over, with DS parroting the poor guy’s expletive). His Dad was an actor, he likewise, never shut up & was a very early speaker.
Son’s now 30 and, with the exception of a couple of ‘teenage grunting’ years he hasn’t really shut up.
DD was speaking in full sentences by 18 months (I think she had to, to get a word in edgewise with her brother). The only sentence her Dad could speak until 3 was, “I broke me leg!” (he’s never broken his leg).
My son didn’t take his first step until nearly a year. My daughter was whizzing around (her nickname was Hurtle Turtle) at 10 months.
Some milestones they’d hit at the same age, others at different ages, just the same as friends children born around the same time.
I was a single Mum with my son, we couldn’t afford a tv (as a broke student) so we’d be mooching out & about chatting about all sorts. By the time my DD arrived I was with now DH (in a proper job lol) but we’d still go out & about, chatting about this & that, exploring the world. Lots of reading books & library time from very little for both. Anything to grow their vocabulary & love of language.
Apropos of nothing, I’ve always allowed swearing (if it’s in the OED then - without being offensive- it’s good enough for me). Learning how, when and where the right language should be used is more important than locking ‘naughty’ words away. A plosive ‘bollocks’ when tripping over doesn’t mean my son littered his crèche, nursery & school experience with random bollockses.
I cannot attest that he didn’t bollocks his way around Uni, but since he came out with a first on a very competitive degree, I doubt he did!