The definition of childhood sexual abuse used here is peculiar enough to warrant suspicion. Note that it includes consensual sexual contact between a 17 year old and a 27 year old, regardless of the genders of the participants. I don’t think that’s particularly rare in society as a whole — it’s not even illegal in most states, and I don’t know of any state that would prosecute it without an aggravating circumstance (e.g. the 27 year old was the 17 year old’s teacher, or the 17 year old was mentally retarded).
Without a control group showing what percent of heterosexual males fall under this definition of childhood sexual abuse, pointing out that 40% of homosexual men fall under it doesn’t provide any information. It may well be higher for homosexual men, but until you have a control group AND break down the “abuse” by ages, and by whether or not it was voluntary, and by the genders of the parties, it’s absolutely totally meaningless to support a claim or speculation that there’s a causative effect. If a large percentage of these boys/young men already self-identified as homosexual before the first “abuse” occurred, what this may be showing is that teenage homosexual boys are very horny and don’t have trouble finding homosexual men in their late 20s to have some fun with (and may be lying about their ages, using fake IDs to get into gay bars and meet older men, etc).
I'd take up that problem with the state. Besides, that might have simply been the LAST occasion in a long string of events extended back into the younger party's infancy.