Who is entitled to have custody over children according to Islamic law?

According to the opinion implemented for fatwa and in Egyptian courts, custody is granted to the mother, whether the child is a boy or girl. The child remains with its mother until the age of 15 after which time he/she is free to decide who to live with. Custody is based on the best interest of the child and the judge is entitled to decide that the child is to remain in the custody of its mother if he sees that this in its best interest.
Hanafi verifiers have maintained that the custody of a woman who marries a man who is neither the child’s relative nor its mahram (unmarriageable kin) is not waived except the marriage is proved harmful to the child. Because the custody of the child is based on its interests as mentioned above, it is important to take into consideration the non-existence of anything that may harm the child, pose any bodily or intellectual danger, or disturb his upbringing on the true essence of Islam and good manners.