Having the right gene is the most important. Of course diet plays a role and clean water as well if your fish has the genes.
I can feed my low quality fh hikari gold daily and the kok will not pop ever since his dad/grandpa did not have kok gene.
On the other hand, I can feed my 4 inch kamfa crap food and his kok will still pop since his dad had great genes.
The one's with the slender foreheads will never have a hump and will look like any normal cichlid. It's a shame to see some being sold with the potential to develop a hump that will never happen. Good to know about the genes.