Yes Mother? is a transformation in The Binding of Isaac, added in the Afterbirth DLC.
Obtained by acquiring any 3 items with the mom tag.
Grants a stationary Mom's Knife that trails behind Isaac and deals 2x Isaac's tear damage on contact.
The knife synergizes as the item would.
This page shows information as of the latest Repentance release.
To see latest up-to date information about this transformation for the new Repentance+ (Online Co-op) DLC, check this page instead.