I wouldn't feel so bad about younger siblings beating you at games. One of the most 1337 gamers that I know is about six or seven now, the younger brother of a friend of mine. He is on level with both of his brothers in Halo, who are exceptional themselves. And have you guys heard of the game The Bouncer? He is literally untouchable in that game, I kid you not.
Once while playing Halo (I don't remember what map, maybe Rat Race) we had just started a team slayer game, so I ran off and wandered through this random portal. It took me to this ledge where a rocket launcher spawns, but it was early in the game so it wasn't there yet. Instead there was this person from the other team just standing there, waiting for it. So I shot her in the back of the head with my pistol. Boy was she confused. Not embarrassing for me, but an embarrassing moment nonetheless.