In his book, The Language of God: A scientist presents evidence for belief, Francis Collins has this to say about homosexuality on page 260:
An area of particularly strong public interest is the genetic basis of homosexuality. Evidence from twin studies does in fact support the conclusion that heritable factors play a role in male homosexuality. However, the likelihood that the identical twin of a homosexual male will also be gay is about 20% (compared with 2-4 percent of males in the general population), indicating that sexual orientation is genetically influenced but not hardwired by DNA, and that whatever genes are involved represent predispositions, not predeterminations.
On the web, there are a number of sources who have quoted the OneNewsNow report that Francis Collins said the following:
‘Homosexuality is not hardwired. There is no gay gene. We mapped the human genome. We now know there is no genetic cause for homosexuality.’”
The problem is – Dr. Collins did not say this. As I noted here, Dr. Collins confirmed to me that he did not make this statement. He did say this:
It troubles me greatly to learn that anything I have written would cause anguish for you or others who are seeking answers to the basis of homosexuality. The words quoted by NARTH all come from the Appendix to my book “The Language of God” (pp. 260-263), but have been juxtaposed in a way that suggests a somewhat different conclusion that I intended. I would urge anyone who is concerned about the meaning to refer back to the original text.
The evidence we have at present strongly supports the proposition that there are hereditary factors in male homosexuality — the observation that an identical twin of a male homosexual has approximately a 20% likelihood of also being gay points to this conclusion, since that is 10 times the population incidence. But the fact that the answer is not 100% also suggests that other factors besides DNA must be involved. That certainly doesn’t imply, however, that those other undefined factors are inherently alterable.
Your note indicated that your real interest is in the truth. And this is about all that we really know. No one has yet identified an actual gene that contributes to the hereditary component (the reports about a gene on the X chromosome from the 1990s have not held up), but it is likely that such genes will be found in the next few years.
Note this part of the quote: “That certainly doesn’t imply, however, that those other undefined factors are inherently alterable.” Sexual attractions may come from the operation of several factors, in different ways for different people. The nature of the cause however, does not directly lead to understanding of how alterable the attractions might be. Perhaps attractions develop with some mix of environment and pre-natal factors. However, once set, attractions for most people seem to be pretty durable.
Go here for the entire post describing the confusion over what Collins said.