@Granny Lawlor There's the Perfect Genetics wherein the heir must be the first child who inherits certain physical attributes of the parents (usually, hair, skin color, and/or eye color).
I haven't looked at the rules recently because it doesn't interest me sufficiently.
Possibly, the Perfect Genetics concept could be combined with any long-term challenge but I've already done Pinstar's legacy twice.
Also, isn't every simmer who loves multi-generation challenges captivated by sims genetics?
These days, I'm preparing for the Big Dreams dynasty challenge (with a clean library clone of one of the Gen3 kids--identical appearance but no non-personality traits, including reward traits, bonus traits, and inherited traits) as well as a variation of the Not So Berry challenge.
Will you join the Tournament Finale, too? Other plans?