You have to love those shirts that brag about accomplishing the easiest task known to humankind. People have to actively try not to have children. There's an entire industry built around the precautions one takes to avoid impregnating a woman. This shirt is even better because it asserts that if your children don't have kids it somehow reflect poorly on you. It might as well say, "Land Ownership is Essential to Personhood" or "Because the Sun God Wills It."
...Actually, those two T-shirts would be pretty dope.