The article is a bit frightening, but to me the problem is an inaccurate reporting of the science, not the scenario they paint. I have access to a university connection, which lets me read over old science articles fairly easily, as well as track down more recent articles which have cited them. The genetic region alleged to be involved in male homosexuality in humans in this article--Xq28--has not had consistent support for this from other researchers. A paper published in September 2006 by Sergey Gavrilets and William Rice in the Proceedings of the the Royal Society B (a moderately high-impact journal in biology) contains a quick literature review on the science of sexual orientation in humans. One of the paragraphs from that I quote here:
"There have been a few attempts to localize the specific genes that influence male homosexuality. The complex nature of the occurrence of male homosexuality in human pedigrees indicates that its inheritance is not a simple Mendelian trait (Pillard et al 1981; Camperio-Ciani et al 2004), making the mapping of individual genes more difficult. A quantitative trait locus (QTL) for homosexuality (Xq28) has been localized to the X chromosome (Hamer et al 1993; Hu et al 1995), but the methodology used in these studies was questioned later (McKnight 1997), and the findings have been difficult to replicate (Bailey et al 1999; Rice et al 1999). Recently, a genome-wide QTL screen for male homosexuality (Mustanski et al 2005) found three 'nominally significant linkage peaks', indicating three autosomal genes that may influence male sexual orientation, as well as limited support for the previously reported X-linked QTL (Xq28). These initial results are only preliminary and require confirmation from additional genetic studies."
The nominally significant linkage peaks means that these three genes had versions which were slightly more often associated with homosexual men than would be expected by random chance; however, in studies where you look at a lot of things at once (as in, say, all genomic studies) you expect that to happen a certain percentage of the time anyway, and you need to examine all individual results carefully to see if they're real or just an effect of looking at a whole bunch of things at once. (Incidentally, 2 of their three genes had less support than I was taught in my genetic analysis classes as the cut-off to warrant further investigation). The limited support for the Xq28 region is that this region didn't have any statistical support in their initial screening, but they went back and looked only at families which had previously been reported, and with these alone the region reached a level they think is significant (but which is still beneath the threshold I was taught as warranting further analysis). So, really, I say they have 1 gene which has a decent probability of being involved, but which needs significant further investigation, and two genes and one chromosomal region which are unlikely to be significantly involved, but which we might as well study in further detail anyway.
Overall, there's no consistent evidence for a "gay gene" or genes in humans. The only reliable predictor for homosexuality is the number of previous male pregnancies his mother has had--more indicates a greater likelihood of him ending up gay. This doesn't appear to be a factor for lesbians, and it's still only a very weak predictor for gay men, but it is at least found in multiple different studies from different researchers. It's important to remember that things can be biological and inborn without being genetic
Also, the whole gay sheep thing is being frequently misreported. I could go into it, but there's already a good analysis of what it's really about over at Slate
(http://www.slate.com/id/2159262/). For those who won't follow that link, highlights include that the researchers are lumping together rams which try to mate with other rams and rams which don't try to mate at all, and seeing if they can make them try to mate with females (whether or not they keep trying to mate with males being considered irrelevant to the farmers--they just want to ensure that their ewes will get pregnant). And, further, they're going about it not by trying to turn rams straight, but seeing if their theories on why rams don't try to mate with ewes (deprived estrogens during fetal development) hold up by doing so artificially and tracking the result. But, perhaps most importantly: the experiments are failing.
In general, distrust mainstream media reports of scientific findings. Most of the reporters working on these things either don't really understand the scientific results, or phrase them in inaccurate ways which they think are more likely to gain public interest. One of the areas this is especially true is whenever "genes for" something are discussed. Add in homosexuality, and it's best to be really skeptical.