What would be the cause of a bent penis? Bad circumcision?

Peyronies/NO! A "bad circumcision" should not have any effect on the curvature of the penis. You may have a more significant problem with a condition called peyronies disease. This is a thickening of a deeper layer of tissue in the penis. See a urologist and get checked out. Perhaps you can have the "bend" fixed and the "bad circumcision" revised at the same time.
?Congenital?acquired. Number of boys are born with chordee which causes penis o be bent downwards. Some boys have a congenitally deviated penis, usually bent to the left. Others could be victims of a bad circumcision. This can happen with poor technique or if baby boy is born with less or a shortage of skin on the underneath of penis. Removal of an even ring of foreskin can cause penis to be bent downwards.