Pursuant to Section § 602(a), the court shall determine custody in accordance with the best interest of the child. The court shall consider all relevant factors including:

(1) the wishes of the child’s parent or parents as to his custody;  

(2) the wishes of the child as to his custodian;  

(3) the interaction and interrelationship of the child with his parent or parents, his siblings and any other person who may significantly affect the child’s best interest;

(4) the child’s adjustment to his home, school and community;

(5) the mental and physical health of all individuals involved;

(6) the physical violence or threat of physical violence by the child’s potential custodian, whether directed against the child or directed against another person;  

(7) the occurrence of ongoing abuse as defined in Section 103 of the Illinois Domestic Violence Act of 1986, whether directed against the child or directed against another person; and

(8) the willingness and ability of each parent to facilitate and encourage a close and continuing relationship between the other parent and the child. 750 ILCS 5/602.

This statutory list, however, is not exhaustive, and the courts have to consider other relevant factors, including:

• Relative economic positions of the parties;
• Non-custodian parent’s child support obligation arrearage;
• Parent’s church attendance with children;
• Frequent changes in residence;
• Instability of second marriage.