I am in the midst of writing about human wholeness, and in order to engage my audience I took up the idea advanced by Dean Hamer of that religion is part of our genetic makeup. I don't usually get into topical pop science, Hamer's thesis is very reductionist and thus smacks of the worse kind of scientism. But I am finding the idea of very engaging.
Engaging this kind of fashionable popular science is very good for preachers even if we find the ideas to be nonsense, explaining our critique is a good discipline.
"The God Gene : How Faith Is Hardwired into Our Genes" (Dean H. Hamer)
I would like to see more UU ministers engage with the science of human nature. There is a very strong case to be made that religion is, in some sense, built into human minds. I don't know anything about Hamer, but from the review at Amazon I worry that you've chosen a poor author to argue against. The idea that a phenomenon as complex as "religion" can be linked to a single gene is, indeed, very far fetched. The best writing I've seen on the topic approaches it from the perspective of cognitive science: religion isn't the result of a single gene, but is a by-product of the very complex ways our minds were engineered to process information. This engineering occurred as a result of natural selection and, like everything else about us, is passed along through our genes, but I don't think genetic science is anywhere near the ability to map our cognitive tools to specific genes.
So, by all means, critique Hamer in your sermon, but please don't let your congregants believe that he's the best proponent of the view that religion is rooted in biology. You'll be doing them a disservice. I've been slowly working my way through _Religion Explained: The Evolutionary Origins of Religious Thought_ by Pascal Boyer, and I recommend it highly. (Your blog is stripping my html but you can find it at Amazon.) It's not an easy read, but if you really want to engage these ideas I think you should go for an author who can make a case worth arguing against. Good luck with the sermon!