Similar themes in Much Ado About Nothing, Merchant of Venice, Frankenstein, and Of Mice and Men

my teacher wants me to write an essay to find the similarities of themes in all four of these novels. This seems like an impossible task, as all four novels are very different, with different themes! Can anybody point out some themes that apply to all four novels at the same time? All I can think of is the theme that men are more powerful than women, but that is all.