On a slightly related note, why is it that one gets lynched on twitter nowadays any time one brings up that "correlation doesn't imply causation"?
Perhaps a third process correlates them.
It's on the person who is implying a causation to state why they think that there is such a causal relationship.
Marriage success and child success have so many other things that they are correlated to: Home ownership, IQ, wealth, zip code, parental educational background, ability to talk about feelings, empath, conflict skill, ...,
So somebody comes around and picks "Marriage" out of this huge list, and somehow now the burden is supposed to be on the listeners to disprove it?
It's seems clear that socio economic status has an enormous influence on child outcomes and is clearly intertwined with other factors.
Do better.