No, that is too simplistic.

Adption is not just genetical. A person can move from northern Europe to southern italy without problem. Its genetics don't need to change for that.

> That means the modern society is not sustainable and cannot adapt to long-term changes.

I don't see that connection. As long as change comes sufficiently slowly, adaptation is no problem. It's mainly that the quicker change comes, the more painful adaptation is. This it unrelated to how sustainable society is.