Look across Europe, and you'll see political leaders with no children of their own.
One of the benefits of parenthood is the daily confrontation with free will—a human nature. Parents may have their child's life, career, and happiness planned out, but a child has other ideas -constantly. Love, patience, teaching, negotiating, scolding— nurture—can help direct the child, but the overwhelming otherness of the child is undeniable. They are not blank slates upon whom the parent exercises his will.
Political leaders without this experience of parenthood may be susceptible to the idea that people are blank-slates, interchangeable units of human capital. As a parent and a teacher, I have seen many brilliant and well-meaning parents and colleagues crash their will and intellect against the rock of a child's independent nature. Now, scale such a hubristic paternalism to a nation. Or a continent.