Fairness Between Children in Spending and Gift-Giving
Question

                How can a father treat his children fairly with regard to giving gifts to males and females? If one of his sons works with his father, how should he treat him?
Praise be to Allah.
    Fair treatment between males and females means treating them 
    fairly as enjoined by Allaah in the verse (interpretation of the meaning):
    “Allaah commands you as regards your children’s (inheritance): to the 
    male, a portion equal to that of two females” [al-Nisa’ 4:11]. So if you 
    give the male two riyals, give the female one. But fairness in spending 
    means giving each one what he needs. A female may need clothes worth two 
    hundred riyals whilst the male needs a hat worth ten riyals. Whatever the 
    case, give him what he needs and give her what she needs, such as if one of 
    them needs to get married, then arrange his marriage and do not give the 
    others something of equal value, except those who have reached the age of 
    marriage – arrange their marriages too. This is the issue of spending and 
    maintenance. Fairness in this case means giving each one what he needs.  

    As for giving voluntary gifts, fairness means giving the male 
    twice what you give to the female, as stated above, as Allaah has decreed 
    their shares in inheritance to be. 

    As for the one who works with his father in trade or in 
    agriculture, if he gives that voluntarily and seeks his reward with Allaah, 
    then reward in the Hereafter is good. But if he says: I want a share in this 
    world like my brothers, each one of them works for himself and invests his 
    money, then his father should give him this, either as a monthly salary or 
    as a share of the proceeds. But he should treat him like a non-relative, if 
    someone like him would be given a salary of one thousand riyals, then he 
    should give him one thousand riyals per month, and if he would be given 
    one-third of the profits or of the harvest, then he should give him 
    one-third, and so on. End quote.