All human attitudes and behaviour are learned or are determined by the predisposition of the genes. What is learned begins from birth onwards. Children learn early from a parental example whether to behave positively or manifest less desirable demeanour. Parents who are responsible and caring towards one another, influence the child to behave likewise towards themselves as well as other members of society. Children who are faced with the animosity of one parent against another, may choose to identify with those who maintain the childs loyalty i.e. the custodial parent, over the non resident parent. Children will view the deceitfulness of the custodial alienating parent as the norm and frequently identify with, and initiate, behaviour shown by the power of the custodial parent. Hence, the child learns early, good or psychopathic traits based on the assumed animosity towards the disadvantaged, alienated parent by developing no conscience or empathy towards that parent, and eventually towards others.
The important question whether children suffer or not from being deprived of one of their parents. There are those who believe, of which I am one, that a child has a birthright to two caring, loving and guiding parents regardless of them being married or separated. Such parents need to be good role models who can influence by example the future thinking and behaviour or their offspring.
REF: Islamic Parenting