The numbering of ancestors with the Sosa-Stradonitz system has proved to be worth while and is customary today.
It was used for the first time in 1676 by the Spanish genealogist Hieronymus de Sosa and later by Stephan Kekulé von Stradonitz who popularised it in 1898.
The principle of this numbering process is simple:
The proband , this means the home person of a pedigree, receives the number 1.
In the parent's generation, the father receives the number 2
and the mother the number 3.
In the next generation, the grandfather on the father's side receives the number 4
and the grandmother on the father's side receives the number 5,
the grandfather on the mother's side receives the number 6
and the grandmother on the mother's side receives the number 7.
The number of each father is always the double of the number of his child..
The number of each mother is always the double of the number of her child +1.
All male ancestors (father, grandfathers, great-grandfathers and so on) receive even numbers,
the female ancestors (mother, grandmothers, great-grandmothers and so on) receive uneven numbers
and each couple of ancestors receives two numbers next to one another.
The ancestor digit for the people of one ascendency result from repeated doubling of the start digit from generation to generation,
for example for the ascendency of the mother (3) the numbers 6, 12, 24 and so on.
The numbers 4, 8, 16 and so on of the father's ascendency show moreover the total number of persons pertaining to the respective generation.
