I have always had a Sim called Kurtis, and he always ends up heavily involved with aliens in some way... he was the first Sim I had who got abducted by aliens (in Sims 2), and his life has become very complicated at points! His alien daughter, Honey, got married and her husband then got abducted by aliens (totally unexpectedly, don'tcha love the spontaneity of Sims 2??) and pollinated by the same Sim who pollinated Kurtis.
This meant that Honey's step-son was also her half-brother, and her husband had been involved with her "mother", which left Kurtis having more in common with his son-in-law than he perhaps should have... it made for some awkward family dinners.
In Sims 3 Kurtis simply met and married an alien, and they had four children. It was a good life, much simpler than the previous game! He's going to be my legacy starter in Sims 4 once I've finished up my current build so I look forward to seeing what antics he and his family will get up to this time.