‘They are cousins, at best.’ Means that there is an objection to the comparison being made between to dissimilar things or ideas.

Idea 1: gold, is being compared to idea 2: lead. But they are cousins at best. There are few uses to which both gold and lead would be suitable, even though they are both heavy, soft metals.

Cousins are related, but have different parents. The characteristics of one family can not be attributed to another simply because they are cousins.

;-D Sometimes car manufacturers like to put a high level name on a low level car, thinking that people will think the lower car is better than other low level cars. Don’t ya love my little mini Cadillac with the 4 cylinder engine and no headroom?

as for your other quote i have no idea

-,Cousins at best means for the better and worst,they always stick together!