This is quite interesting.
Several years ago, Trevor Hart and other scientists from the Centers for Disease Control and Prevention in Atlanta studied 205 gay men to find out why some them consider themselves catchers or pitchers.
From the results, this is what they found out:
Tops were more likely than both bottoms and versatiles to reject a gay self-identity and to have had sex with a woman in the past three months. They also manifested higher internalized homophobia—essentially the degree of self-loathing linked to their homosexual desires.
Versatiles seem to enjoy better psychological health. Hart and his coauthors speculate that this may be due to their greater sexual sensation seeking, lower erotophobia (fear of sex), and greater comfort with a variety of roles and activities.
Self-labels are meaningfully correlated with actual sexual behaviors. That is to say, based on self-reports of their recent sexual histories, those who identify as tops are indeed more likely to act as the insertive partner, bottoms are more likely be the receptive partner, and versatiles occupy an intermediate status in sex behavior.
It's a fun read. It gave me some insight in my self-label.
here's a direct link to the research