Pardon my ignorance, but aren't the skulls often shaped a bit differently? If the textbook was just showing that and not saying something about one shape making a certain race superior, is that still a problem?

Different races will often have little differences right? My favorite example is the gene variant ABCC11 that is extremely common in South Korea. It limits the production of odorous sweat by reducing the activity of apocrine glands. I think it also affects whether ear wax is wet or dry. I'm kind of jealous of that one and am waiting for CRISPR to be available for it. Well maybe not, but I'd at least think about it.