The mystery of having a son ?

Hey, so far, never heard of an "official" way to get a son spawning at your yearly youth coming.

Heard lot of infos as:

-You need to be more than 34
-You need to be at the same club for 10 years
-You need to have a player who retired after being at your club for 10 years
-The chance is 1/10.000

does anyone have the clue ? For the FM2017 full version of course

and please, so much people are speculating on things about FM. Maybe because this game if a lot about "minding" and whatever. Don't confuse everyone with theory of your own.

clear sources and screenshots are welcome

thx a lot