Nah, Geralt and Yennefer were married. Witchers are sterile due to the mutations and Yennefer because she is a sorceress. Ciri is his (and Yennefer's) unintentionally adopted child. Geralt died defending a elf from a lynch mob, and then Yennefer (a sorceress) tried to bring him back which cost her life. So technically both of them should be dead. Geralt is currently suffering from amnesia so he doesn't remember his past life, and his love of Yennefer, or why he is alive.
Damn, that sounds crazy. I love the Witcher lore. Never read the books but I want to. Anyone read the comic? It's pretty good. They said they were influenced by BPRD and Hellboy and it definitely has a Mignola vibe.