Hanging up pictures of children inside the house

It is not permissible to
hang up pictures at all, whether of children or adults. That is because of
the stern prohibition narrated from the Prophet (peace and blessings of
Allaah be upon him) against keeping pictures and his command to ‘Ali (may
Allaah be pleased with him): “Do not leave any image without erasing it or
any raised grave without leveling it.” Narrated by Muslim, 1/66 

Hence pictures must be removed, erased or burned and not
kept. 

Hanging up pictures of animate beings inside houses or
elsewhere deprives the people of that place of a great deal of good, which
is the angels’ entering that house. It was narrated from Abu Sa’eed
al-Khudri (may Allaah have mercy on him) that the Prophet (peace and
blessings of Allaah be upon him) said: “The angels do not enter a house in
which there are statues or images.” Narrated by Imam Ahmad; Saheeh
al-Jaami’, 1961. 

It is permissible to hang
up pictures of inanimate things such as trees, mountains, seas and natural
views, or other inanimate drawings, without being extravagant.