on head
on (one's) (own) head
Being one's sole responsibility to bear. I won't rat you out, but if you get caught cheating it's on your own head! She's the one who cheated, so in my book, their marital troubles are on her head.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
on someone's head
Fig. [for something negative] belonging only to one person or group. All the blame fell on their heads. I don't think that all the criticism should be on my head.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.