Here is a recent interview, Michael Ruse - Philosophy of Race and Ethnicity, where he argues that racial differences are all cultural:
I think 4:59 what see is it's the there are differences 5:02 but the differences are cultural not 5:05 genetic and so that's why for instance 5:07 it Living in America, I'm very keen on 5:11 programs of diversification and that 5:14 sort of thing. you might have to do this 5:16 but let's make sure that people who are 5:19 not. you know, white Anglo sax Protestants 5:22 are not as it were pushed into the same 5:25 group as the rest. I mean we see this 5:27 don't we say with Catholics think of 5:29 Cath Catholics in the 19th century as we 5:31 go into the 20th century clearly way 5:34 below white Protestants now what this 5:38 because Catholics had some genetic 5:40 defect no or Jews no it was because they 5:44 didn't have the 5:46 opportunities Jews for instance we all 5:49 know how Harvard wouldn't let Jews in. we 5:52 know that we know that so the point is 5:55 what I'm saying is I think that there 5:57 are if you like racial differences. 6:00 clearly some are genetic but I see no 6:02 reason to think that any of these have 6:05 any significant thing on intelligence 6:08 and it's all cultural, we can change it.This bizarre, as he wrote many books on Darwinian evolution. How would intelligence ever evolve, if it were not inherited in the genes?
Another well-known veteran of the evolutionist-skeptic community is Steven Novella. He also has a long and prolific history of scientific skepticism, rational thinking, and debunking pseudoscience.
Now Novella goes to rationalist meetings denying human sex differences. See When Skeptics Get It Wrong: Debunking The Debunker for a discussion of his errors:
Obviously, Dr Novella’s definitions don’t represent the consensus of biologists. Indeed, they weren’t even written by biologists, and they certainly didn’t come from biology journals. ...Thirty years ago these guys help win the wars against Creationism, by arguing science, reason, Evolution, skepticism, and rational thinking. Now they make these leftist arguments that are not based on any science.Another interesting (and telling) component here is the number of biologists who are silent on the topic. That alone rings my skeptical alarm bells. Why would biologists be afraid to say sex is NOT binary in the current social climate? ...
Humans are definitely sexually dimorphic, and no one is arguing against that basic biological fact. However, although there are many ways to be male and female, there are still just two sexes.
The fact is that sex is binary in humans and other mammals. People are either male or female. And nearly all human trait, whether physical, psychological, or behavioral, are heritable, and lead to genetic and racial differences.
These issues are not complicated. Whether Catholics are, on average, higher or lower in intelligence than Protestants, I do not know, but it can be measured. There is evidence that Ashkenazi Jews are of higher intelligence. Some of that is questioned by The myth of Jewish intelligence. I have not examined it myself.
Left-wingers have certain egalitarian goals, and they get upset at the idea of racial, sexual, or genetic differences, even when those differences are plain to see. Apparently those political goals have corrupted the thinking of people who are otherwise advocates of hard science.