That all was such a screwed up ridiculous storyline, The writers back then fell in love with weird ways to get pregnant, for sure.
And then we have the Kiriakis clan. Victor did father Bo, but I think he is Vic's bio only child. Justin was the son of Vic's brother, and Sonny is HIS son. Justin married Adrienne Johnson (Steve's sister), there were other boys who had been adopted, and are who Sonny refers to as his brothers. (And Jack Deveraux is brother to Steve & Adrienne......married Jennifer Horton, daughter of Bill & Laura Horton). Xander is another son of a brother of Vic's, who also has come under Victor's care.
And, of course, we cannot leave out Stefano DiMera's offspring, can we. All with different mothers, hard to keep track, so hope those with better memories than me will help here. Let's see.......an affair with Vivian Alamain led to the twins Stefan & Jake. Her manservant, Ivan gave both away but she found Stefan (whom Gabi eventually married, but he died taking a bullet meant for his mother, Vivian, by Detective Lani. ) When Jake turned up looking exactly like Stefan, Ivan admitted there had been twins. (Fans loved Stefan, & the actor, so the writers thought up the unknown twin so they could bring the actor back). Stefano also fathered EJ, via Susan Banks (and that story is so far fetched is hard to describe). Susan was enamored of Elvis, Stefano dressed up like him, got Susan drugged a bit by Dr. Rolf, and managed via insemination or something, to impregnate her. EJ stands for Elvis, Jr. Stefano also fathered Lexie, Abe's wife, who died. He also fathered Renee' DuMonde, Megan Hathaway, Benji Hawk (that was tragic story, Loved Benjy & the Hawk family). Then there was Chad.....Mother was Madelyn Peterson.
And of course he raised Kristen & Peter Blake, who some say were adopted, but I only remember Stefano being guardian. However, Kristen decided in her 40s to take the DiMera name.
EJ fathered Johnny DiMera, Sydney DiMera by Sami Brady.
Sami also gave birth to Will Horton, & Allie Horton via Lucas. Allie is Johnny's twin. Yep Sami got around as well.