Another reason to believe that anal sex is not healthy:
A friend of mine worked as an editor for a doctors medical magazine. She edited an article that stated as fact that with extended abuse of the anus in anal sex the "victim" would eventually ruin the sphincter muscle thereby needing a bag to hold their feces.
Doesn't sound healthy to me...
1) That's actually not the whole truth, and anal sex does not ruin the sphincter, although other practices can
2) Many gay couples don't practice anal sex, and some straight couples do. So what's the point here?