In a custody dispute, the court does not rule on what either parent prefers, but on the child's best interest (çocuğun üstün yararı).
Factors
Age of the child, attachment to each parent, stability of the home, living conditions, schooling, parents' physical and mental health, the child's own view (above a certain age).
The social report
The court orders a social worker to interview both parents and the child and to visit each home. The report carries significant weight.
Joint custody
Possible since 2017, but only when the parents can co-parent maturely and it serves the child's interest.
Later modification
Custody can be revisited when circumstances change — abuse, neglect, relocation abroad, serious health change.