Miroku is a monk, but he's far from holy.  It's safe to assume that he's older than the rest of the group.  Miroku is cursed with a black hole in his palm.  This wind tunnel was given to his grandfather by Naraku and is a generational curse, and was passed on to Miroku after his father's own wind tunnel sucked him in.  As long as Naraku lives, Miroku will be plagued by the wind tunnel, and if he dies before he kills Naraku, then his child will be cursed with the void.  This is  where Miroku's famous line comes from, "Will you bear my child?" is a question he asks every pretty girl he meets, including Kagome.  Miroku's lecherous tendencies frequently get him into trouble, and in Episode 28, it nearly gets him killed when he's attacked by a giant demon masquerading as a beautiful woman.  Miroku has a bad habit of putting his hands on the girls in the group, and is frequently seen to have his mitts on Kagome's or Sango's behind.  None of them are particularly happy with this aspect of his personality, excluting Miroku of course.  Miroku is strikingly handsome in the world of Inuyasha, and frequently leaves princesses pining for him after he departs.  Miroku is also a bit of a fraud, and always detects an "ominous cloud" hanging over the finest lodging in the area, and offers to "cleanse" the area in return for food and a nigh's lodgings.  Because of him, the Gang occasionally gets to spend a night in a cushy palace rather than on the damp ground.