Members of the fathers' rights movement and their critics disagree about the correlation of negative developmental outcomes for children to sole custody situations. Social scientist V. C. McLoyd states that father absence covaries with other relevant family characteristics such as the lack of an income from a male adult, the absence of a second adult, and the lack of support from a second extended family system and conclude that it is the negative effects of poverty, and not the absence of a father, that result in negative developmental outcomes. On the other hand, Professor Craig Hart states that although the consequences of poverty and having a single parent are interrelated, each is a risk factor with independent effects on children, and Silverstein and Auerbach state that the negative outcomes for children in sole custody situations correlate more strongly to "fatherlessness" than to any other variable including poverty.