A court considering parents conflicting claims to custody and visitation with their child must make its determination based upon what is in "the best interests of the child." (DRL Sections 70; 240). In determining the best interests of the children, the court must evaluate the totality of the circumstances (see Eschbach v. Eschbach, 56 N.Y.2d 167, 171–174, 451 N.Y.S.2d 658). Among the factors to be considered in making a best interests determination are the quality of the home environment and the parental guidance the custodial parent provides for the child, the ability of each parent to provide for the child's emotional and intellectual development, the financial status and ability of each parent to provide for the child, the relative fitness of the respective parents, and the effect an award of custody to one parent might have on the child's relationship with the other parent. The court must also consider the stability and continuity afforded by maintaining the present arrangement. (Lieberman v Lieberman, 42 A.D.3d 1144, 38 N.Y.S.3d 81 (2 Dept., 2016)). The best interests rule escapes precise definition but has been explained in a series of Court of Appeals decisions dating back to the 1970's. 

In 1976, in Ebert v. Ebert, (38 N.Y.2d 700, 382 N.Y.S.2d 472 (1976)), the father's modification petition centered on the fact that the two older children, had indicated during the summer vacation visit with him, a preference for remaining with him permanently. There was no claim that the mother, who the parties agreement provided was the custodial parent, was not fit. The Court of Appeals observed that the best interests of a child, often require the overbalancing of subjective desires by more dependable objective criteria and that the findings of the nisi prius court must be accorded the greatest respect. Other than the children's wishes, there was no change of circumstances to justify a modification of the custodial arrangements. The court held that the disparity between the creature comforts and amenities that living with the father would bring and those lesser ones provided by the mother was not a material change of circumstances warranting a change of custody. Furthermore, the separation of siblings, where, as here, the custodial parent was fit is to be frowned upon. The order which granted custody of the two older children to the father was reversed.