N = 3, we intentionally never baby talked to our kids, and spent a lot more time reading them novels and other things without pictures or simplified language than (I'd guess) most people do (we did also do plenty of picture books), and their language development was in all three cases way ahead of schedule.
Could just be luck (well, genetics, probably) I guess. Maybe they'd have developed even faster if we'd used baby talk. One shitty thing about parenting is it's really hard to tell what helped, what hurt, and what didn't matter at all.
>...their language development was in all three cases way ahead of schedule.
I would put a lot more of it to having (seemingly) engaged parents. Even a backwards strategy enacted by a loving parent who is consistently trying their best is likely to outperform the result that most can manage (owing to time/money/education/etc).
That is my belief as well: being there, listening, interacting lovingly, paying attention is overwhelmingly more important than a particular technique.
I've never baby-talked to our son, but I do coach him to say things that are within (or almost) within his speaking capabilities. So for instance, this evening we were reading The Gruffalo, and he pointed to the fox and said, "Fox eat!" I said, "The fox wants to eat the mouse?" He said, "Yeah!" So I tried to coach him to say "Fox eat mouse". He got as far as "Fox eat there"; maybe he'll get to "Fox eat mouse" in a week or two.
I did this as well with the same results (but also have reason to believe genetics played a major part). But I'm not sure we're optimizing for the right thing. I'm far from convinced that accelerated language development is a good thing. I think development may suffer in other areas.
Why would you believe genetics plays a part? There is minimal evidence for that. You have actual evidence for things like your higher than average time engagement, nutritional indicators, as well as health and dental care. You probably live somewhere with decent air and water quality. Then of course the likely fact that parents have relatively prodigious vocabularies, fluency and articulation. This is why your kids are smart.
Lots of evidence that genetics have a large influence on early language development, especially speech, if you care to look. E.g. this study finds genetics contributing over 60% of variance: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3851292/
No doubt when we start looking at impairments and deficits that you can find plenty of situations where a high proportion of the phenotypic variance is heritable. But when you restrict the study to the top 60th to 95th percentile (which we are discussing here) I don't think you will find particularly strong relationships.
It's not genetics or a language strategy, just engagement.
Compare a toddler living in a ghetto concrete jungle to one who takes daily strolls through Central Park or Suburbia. The enrichment of parents teaching about the trucks and the trees and the lady with a purple hat pays massive returns.
I did goo goo gaa gaa for the first 6-8 months since you can tell there’s really nobody home up there yet and it’s cute and engaged my other kids to play with the youngest. But yes. Mine seem fine as well so I doubt CDS is going to make/break a human being.
Could just be luck (well, genetics, probably) I guess. Maybe they'd have developed even faster if we'd used baby talk. One shitty thing about parenting is it's really hard to tell what helped, what hurt, and what didn't matter at all.