It's not clear where the numbers on gays are coming from, but a quick look at the methodology section of the study referred to in the Slate article shows that it has the usual fault of such studies: it only reports data one people willing to talk about their sexual activity. It's not unreasonable to postulate a positive correlation between valuing chastity and reluctance to respond to such a survey; also, I see for instance no reporting of religious preferences in the data, which one might hope would have some correlation with activities of various sorts. The reporting of adolescent data was to some degree mediated by the parents, so there's another possibly quite strong bias source there.

BTW there are some interesting statistical things going on in the graph from the Freakonomics guys. It's pretty obvious that the drop attributed to the current recession is at best too small to care about. It's the bouncing around in the middle that is worth looking at. First, the drop during the depression is quite real (and sends a message that the current recession is comparatively mild in its effects just far); but then, around WW II, the rates bound all over the place, first picking up sharply just before the war, then dipping again during the first half of the decade, and then giving a huge spike in the latter part of the 1940s. Well, if people put off marrying in the depression, there is a tendency for a rebound; and if they cannot marry because they are overseas due to the war, there is also a tendency for a rebound. And if the rebound is strong enough to get a lot of people to marry early, then there will be a drop in the rate in subsequent years because of the deficiency in people who otherwise would have married later. Conversely the bulge in the 1970s is caused by the boomers producing a larger percentage of the population at peak marriage ages; people are marrying later, but there's also a bulge of people who, if they were ever going to marry, have gotten it over with.

I want to second C Wingate's concern about all such studies in relation to the sampling and surveying methods. We saw one in England not long ago, reporting a 1% rate for persons who identified themselves as gay or lesbian, which then extrapolated that figure to the whole population. The "Heisenberg" factor (the effect of the question merely being asked) relates to the willingness of people to speak openly about sexuality and sex. Just as, as CW points out, there may be a correlation between a preference for chastity and an unwillingness to participate in such a survey, there is also a likely unwillingness to be open about "minority" sexuality in a social setting in which it is disapproved. Generalizing to the whole population in both cases is very likely misleading.

And if I may venture another comment, the second link, in attempting to point out that the rest of the population is as promiscuous as gay males are said to be, is not exactly making a positive point. The chart in question rings my statistical alarms very loudly, but to the extent that it is taken seriously it says that anything we have to say about chastity is have next to no impact.

C.W., perhaps not so much a positive point as the rationalizing of a negative. Again, the most that should be said, is that for the 3.2 million users of this particular dating site, multiple partners are equally common for both gay and straight "daters." Whether members of the general population have the same average number of partners as the "dater set" remains an unknown. However, I think it safe to say that the "promiscuous gay male" is no more (nor less) a reality than Don Juan and his confreres. In the meantime, the church should promote the ideals of fidelity and permanence to all of its children.