Statistics reveal that married or partnered males have fewer wet dreams than un-partnered ones; also, younger males have more frequent wet dreams than older men. However, there is little evidence of a correlation between frequency of masturbation and frequency of wet dreams.
One thing that might influence the frequency of wet dreams is the level of testosterone produced. According to a study by Finkelstein et al, 90% of the subjects taking a high dose of testosterone experienced wet dreams, compared to 13% of the subjects taking none.