It is interesting that the average age of conception in the series is 33 years (21 generations in 700 years) It seems an old age, historically.

The age of coming of women in my country was 15 years old. I think it was common in Latin America. The age of consent is now 16 yo. In Colombian is 14 yo, I think.

tl;dr:

"15 direct male-line descendants related genealogically to both Leonardo's father and to his half-brother"