I aged down the Sims 2/Sims 3 sims.
Bella Bachelor(Goth) to a child and created her mother, father, and brother in CAS using her genetics (Jocasta, Simis, Michael).
Mortimer Goth to a child and created his parents in CAS using his genetics (Gunther, Cornelia).
Don Lothario to a child and created his parents in CAS using his genetics (Adriana, Nicolo).
Dina and Nina Caliente to children and created their parents (Nighat (changed Katrina's name and how she looks), Flamenco created in CAS using their genetics - really should have made him an alien but was not thinking at the time!).
Macolm Landgraab to a child (same parents - think aged them down to young adults though and changed looks).
I have not gotten that far with it yet - they are all friends as children right now and about ready to age to teens.
I am curious to see if like Bella and Mortimer's kids end up looking anything like the Cassadra and Alexander that are in the game now.
Have fun and do keep us updated! I have not played my save for awhile - really need to get back to it!