Memes

On the blankets thing, my understanding is that there was a single incident during the siege of Fort Pitt where a Swiss mercenary captain handed out some linens from their smallpox ward with the hopes that it'd kill the sieging natives. There's no proof the blankets killed them either (as opposed to an epidemic already circulating), as supposedly smallpox can only survive 24hrs outside of a host.

However, the widespread pandemic that is known to have killed thousands was not intentionally caused by settlers. That didn't occur for another 60~70yrs. The single account that claimed the US government committed genocide via biological weapons has supposedly been fairly thoroughly debunked. Of course, the smallpox had to come from somewhere, but it's unlikely that it was intentional.