I don't understand. Do we need more people? Is there a population shortage? Six billion isn't enough for what exactly?
I'd say we need more smart people.
It would be scary if the smart people stop having kids. The world would be taken over by stupidity.
Then I have a simple suggestion based on the same wide-ranging generalisations you base your reasoning on:
Make marriage illegal for all the heterosexual couples who believe that same-sex marriage should be illegal.
I don't understand. Do we need more people? Is there a population shortage? Six billion isn't enough for what exactly?