Him and his father both have some odd idea that they have such good genes they need to spread em around to pass down their superior semen. It isn’t exclusive to them (see Nick Cannon and others) but it’s also a common white supremacists or evangelical belief (see Great Replacement Theory and the Quiverful movement).
It’s so ingrained in our life processes. You know Calories? The capital C version(or Kcal in some countries) is 1000 calories. What do they measure? The potential heat whatever is being measured can generate. Our fuel intake is measured by how well it burns.