why did the narrratoer say that the distribution of various kinds of spirit our tribe had been from the beginnning capricious and vagrant?

The narrator says that the distribution of the spirit in their tribe was from the beginning capricious and vagrant because a man could be the biological father of his son but in temperament and disposition,the son and father would be two totally different people. He talks about Mourad who was the son of Zorab but in spirit he was more akin to Khosrove who was a man of placid disposition and nothing could unnerve him,not even his own house on fire. Mourad was believed to be the natural descendant of this man though his father was a different man,practical in nature. This was how it worked in the tribe, men had biological as well as spiritual fathers.