It is very interesting. I see IQ as being like all traits with a genetic component - as Daniel Dennett says, the genotype keeps the phenotype on a leash. You can vary so much depending on your environment - but there are limits.
I was taken into care and adopted as a toddler having been locked in a room alone all day, every day, since I was 6 weeks old. My amom was very highly strung, both parents had left school at 15, and my amom in particular had no time for education, especially for girls. The only books were the bible, and a few Mill & Boons.
No-one knows how I learnt to read. By 8 I was 5 years aherad of my peers. I was confused - my teachers and parents were clearly not on the same page. I thought grown-ups had something wrong with them that meant they couldn't see what children could understand.
The next 30 years were difficult (long story) but now I've found a nesting place in academia. I have dd, nearly 4. She's bright, and I worry for her. I want it to be different for her so I am definitely providing more input and more stimulation.
But I also know that I am very self-driven compared to some of my peers and that also comes from my background. So I am not teaching dd anything much - just talking about stuff and trying to follow her natural interests. She taught herself to write but she hasn't learnt to read. That's her choice. I'm sure I could teach her to read but she isn't actively doing it so I think it's better to leave it alone.
I don't want her to have the difficult years - but I don't want to take away her capacity to be self-motivated either. I don't want to over-compensate for my own experience.
I doubt whether parental input can make a child gifted in the usual sense - but it can make some kind of difference. I saw a lot of kids from pushy backgrounds and private schools burn out at university. They did OK generally - but only OK.