The last strategy to manage tension (projection onto a child; see Concept 3) was so common that it became Bowen’s fourth theoretical concept—the nuclear family projection process—by which parental undifferentiation in the father-mother-child triangle impairs one or more children, as they inadvertently project their emotional immaturity onto a child, a target outside of themselves. Bowen posited that this process occurs to some degree in all families, but to a lesser degree—with less impairment—in families with a greater degree of differentiation (Bowen, 1978).