I'm a grammar, spelling and punctuation pedant and make no apology! Errors just jump off the page at me and assault my senses. I admit to erasing or obliterating erroneous apostrophes whenever possible!
Although spelling and punctuation were emphasised when I was at school, grammar was, bizarrely, overlooked, and I have never formally been able to tell my adverb from my pronoun.
I have however always been an avid reader, and perhaps I developed an eye for correct usage because of this.
My daughters, aged between 24 and 32, all write and spell beautifully, and I think my input during their school years was probably a contributory factor. I was never aware of poor marking by their teachers, but then again their homework did not often contain errors as they would always ask me for guidance when unsure!
When it comes to texting, I find that the youngsters in my life very quickly revert to 'proper' English after exchanging just a couple of texts with me. I always write in full, and, interestingly, they respond in kind very quickly!