on one's 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.
See also: head, on
Farlex Dictionary of Idioms.

on one's head

Also, on one's own head. As one's responsibility or fault, as in If the police catch you speeding it's on your own head. This idiom, dating from the 1300s, conjures up the image of blame or guilt falling on someone's head. Also see off one's head.
See also: head, on
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • on (one's) (own) head
  • on head
  • just deserts
  • the heart wants what it wants
  • caught between the devil and the deep blue sea
  • get taken to the cleaners (by someone)
  • caveat
  • caveat emptor
  • a/one side of the picture
  • a/one side of the story