Okay, I'm gonna come in here and be technical. Sodomy is either oral or anal copulation and copulation is "sexual" intercourse; therefore, sodomy is sex. Whilst there's a negative connotation attached to the word, seems that folks were enjoying both the giving and receiving of anal sodomy since bibical times and probably before.
Is it thought to be a submissive act because of the subordinate position? If so, then even entering the vagina from behind would be a submissive act, no?