Using GSS data, I found in an earlier analysis that gay men and lesbians had higher average IQs. To check this, I examined mean IQs by sexual orientation for adolescents from the Add Health Study. IQ is measured with a vocabulary test. Students were asked if they were ever sexually attracted to a female and/or a male. I limited the analysis to whites: the overall mean is 104.3 (it is high because the mean for the whole sample that includes many NAMs is set at 100).
Mean IQ score (sample size = 6,145)
Bisexual female 108.1
Straight male 105.9
All whites 104.3
Bisexual male 104.3
Straight female 104.0
Gay male 102.6
There are a range of means, but the only statistically significant difference is between bisexual and straight females. It's close to one-third of a standard deviation difference, which is fairly small.
Unlike the GSS analysis, lesbians and gay males do not appear to be smarter than other groups. The GSS asked about sexual behavior, not attraction. It might be the case that smarter people are more likely to act on non-conformist desires.