Yes, it seems likely the explanatory power is much less than 25%. And it is also not exactly clear what is being "explained" unless/until some sort of causal genetic pathway is established. Which seems unlikely anytime soon.
And, I agree, sexual orientation is a social construction. I actually see all of the above as a great tool for deconstructing this idea of a unified "thing" called sexual orientation (thus the idea of "homosexualities", for example, as one place to start talking about that). Likewise with race. We can't discover a "white gene" or "black gene" but we might find a gene that influences melanin production. Then we can show how little correspondence this gene has with classic ideas about "the races." We can already do this with phenotypic characteristics historically associated with races. We can throw gender in here as well. Even if posession of certain chromosomes, for one example, is correlated with identification as a certain gender...it doesn't explain all the variation out there. Most of my students, somewhat surprisingly, either don't come into class knowing this or only have the vaguest of notions about it.
I would also agree with and extend your idea about of a "gradient of human sexual activity." There are probably a multitude of gradients we could place people on with regards to sexuality (we could use the Klein Grid as one such jumping off point), and again social forces shape how we tend to think and perhaps even how we're able to think about those.
I guess I need to read the book you reference, or at least that chapter, to see what they're asserting.
Re: *rolls eyes*
And, I agree, sexual orientation is a social construction. I actually see all of the above as a great tool for deconstructing this idea of a unified "thing" called sexual orientation (thus the idea of "homosexualities", for example, as one place to start talking about that). Likewise with race. We can't discover a "white gene" or "black gene" but we might find a gene that influences melanin production. Then we can show how little correspondence this gene has with classic ideas about "the races." We can already do this with phenotypic characteristics historically associated with races. We can throw gender in here as well. Even if posession of certain chromosomes, for one example, is correlated with identification as a certain gender...it doesn't explain all the variation out there. Most of my students, somewhat surprisingly, either don't come into class knowing this or only have the vaguest of notions about it.
I would also agree with and extend your idea about of a "gradient of human sexual activity." There are probably a multitude of gradients we could place people on with regards to sexuality (we could use the Klein Grid as one such jumping off point), and again social forces shape how we tend to think and perhaps even how we're able to think about those.
I guess I need to read the book you reference, or at least that chapter, to see what they're asserting.