You shouldn't play favorites with your kids.
Tara has two children and one of them is a lot less of a hassle than the other.
Tara wants to buy presents for her kids.
Tara makes sure to give both of her children gifts that they want because she cares for them both.
Tara always buys nicer presents for the kid that gives her less trouble.
Tara's children both grow up knowing their mother loves them and it increases their odds of being well adjusted.
Tara's children recognize she has a favorite and it affects both of their attitudes negatively as they grow up.