Does this prove IQ? No. however, I would be astounded if there was no relationship (just looks, voice, height, thought patterns, but no IQ correlation).
At the same time, my kids are quite different from each other. However, my siblings' kids reflect their parents and have diverged significantly from my family far more so than my kids diverge from each other.
My eldest brother (as an example), earned good money but spent it all. He put very little love or effort into his kids, despite him being raised in a household of caring and sharing. He's also a drinker and drug taker. His kids all have troubles with drugs and alcohol.
This is nothing like my family. We have continued down a path of caring and sharing and support quite a few community activities.
I'm not inclined to equate IQ directly, but, I am strongly inclined to say "there is a lot more than just looks that gets passed down to children".
My eldest sister is a behavioural clone of her biological mother. They didn't know each other until their 20s. That was the moment I knew that behaviour could be inherited by children, because my eldest sister is an aggressive hedonist. No drugs, just wild partying and ladette behaviour.
The other aspect of this article that is true is that luck favours the prepared. Some people send their kids to private schools so they can Mingle with other well-to-dos.
What I do like about today's society is that there is a wealth of opportunity if you look for it, regardless of socioeconomic status. I am a huge believer in opportunity but I totally reject political correctness (and any other prejudice for that matter, PC just happens to be the most popular prejudice today).