Witnessing violence between members of one's own family is known to exert a very significant impact upon children and young people. PTSD, and Attachment difficulties, amongst others.

Domestic Violence, if unchecked by the parents, is likely to constitute a form of Emotional abuse or Neglect as by definition other peoples' needs (rather than the child's) are being prioritised.

This means that Child Protection/Safeguarding Services may need to be involved at an early stage. To "turn a blind eye" to these concerns may be seen as a subtle form of collusion by a worker.

There are a series of helpful reports, recommendations and research data about this here