on your head be it
on (one's) (own) head be it
The blame, consequences, or responsibility of a risky, dangerous, or foolish decision or action belongs to someone and no one else. If she wants to quit a high-paying job to chase after some fantasy of being a travel writer, then on her head be it.
on your head be itor
on your own head be itmainly BRITISH
You say on your head be it or on your own head be it to tell someone that they must accept the consequences of a particular action. This is not the time for such a discussion. But if you insist, on your head be it. If you choose to ignore my generous offer, then on your own heads be it.