Spiritual energy, or jing, is a powerful substance that forms the essence of who and what we are. It is the primal energy of our life. Jing is the deep foundational energy reserves of the body and it is this energy that determines one's ultimate vitality and the quantity and quality of one's lifespan. Jing is our material body, cellular density, energy stores, our reproductive potential, our DNA and our seed. It also determines a person's magical potential.
Individuals are born with different levels of spiritual energy, with some having more than others. Certain clans or families have been blessed with members who naturally have high levels of energy. However, this energy can be increased in life through training and practice. Jing is used during magical spells or physical activity, but slowly recharges itself over time. A man summons his jing and focus it in his nether regions before intercourse in order for conception to happen. This process takes about one hour through meditation. Instead of shooting out white little swimmers, he passes on his energy to the woman during release.
The issue is that if a man can summon his jing to pass on, it stands to reason that he can determine the amount of jing that is passed on, willingly making his offspring stronger in spiritual energy. I would like this process to be randomized, so that nobody can intentionally be given an advantage over others. How can I make this happen?