A young boy becomes a roach- literally all I remember. However, the side story I do remember. His sister is some kind of super genius who didn’t speak until she was five and when she did finally speak she created a board game. She spends her day in front of the tv counting the number of times the commercial for the board game plays and how much money she is making.
The little sister Winnie is from Lee Wardlaw’s book My Life as a Weirdo (also titled Seventh Grade Weirdo). Is it possible that the roach part is from some other book?
I had it backwards. The roach becomes a boy in “Shoebag”. Shoebag also has a little sister that watches tv all day, which is probably how I combined it with Winnie’s features. Shoebag is by Mary James. Solved!
Beetle Boy by M. G. Leonard?
Wait sorry, I meant Beetle Boy by Lawrence David. Illustrated by Delphine Durand?