Sovereign dynasties - genetics, reputation and eugenics
A few ideas that I think would enrich the dynasty system.
Genetics
I would like to propose a system be implemented into the game that would take genetics into account. That is, when you as a sovereign have offspring they will inherit certain traits from you (good and bad). Perhaps your character is a naturally hardy albino that is an alcoholic. Some or all of these traits could be passed to your children. This may make you (and by extension your dynasty) more or less attractive to other royal families as they strive to strengthen their dynasties by choosing good genetic stock.
Example -
Family kept a family genetic deficiency secret to secure a marriage for their son, now this knowledge comes to light but only after the newborn of your lineage show symptoms. What do you do?
Perhaps, as in the real world, inbreeding would have consequences. the closer someone is related could lead to a higher probability of genetic anomalies in their offspring.
Reputation
I think reputation or prestige is going to play some part in the game but I must admit I am unsure how much or to what extent. I would like to see reputation extend to the dynasty system. The way the outside world sees you would affect your chances of trying to marry into a family.
Eugenics
Eugenics is the study of using selective breeding in humans to improve or control the species.
To put this in the correct geek context think of the Dune series by Frank Herbert. Over the course of many generations, through the use of a clandestine breeding program the Bene Gesserit attempt to create the Kwisatz Haderach, a man/god.
Perhaps this notion of trying to attain or exploit certain genetics through the use of eugenics could be used in the game. This would make certain marriages more appealing or perhaps necessary if you were trying to breed in or out certain attributes.
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I think that if the dynasty system would be developed correctly then it could add a lot of depth and strategy to the game and has the potential to be one of the most interesting aspects. It could be the cause of wars or peace treaties.