Screamo is a subdevision of Emo
which is a subdivision of Punk Rock
which is a subdivision of Punk
which is a subdivision of Rock
. Screamo started in the mid 90s when a young man who couldn't sing begged his four friends to let him join their band. Having no talent at all and hurt by their rejection he screamed "LET ME BE IN THE BAND!"
The band was both shocked and impressed by their friends ability to scream and let him join out of sheer fear.