This is an interesting idea- that I definitely hadn't considered. It says, somewhere in book 4, that the Go Backs had sort of turned off recognition- because of their high death rate- and just bred without it. Well, Kahvi is a Go Back. If figured she would get pregnant the way any Go Back would- which I figured was similar to how any human would get pregnant... but trying. She had sex numerous times with Rayek- presumably, eventually, she would have gotten pregnant by him. It could have been the same with Windkin. She probably didn't just sleep with him once. She probably slept with him until she finally got pregnant by him. As for Cutter- I just figured she was giving it a go. Maybe she knew what was the right time of her cycle. Who knows? I wonder though... having considered this- do Go Backs get their periods? How do they breed without recognition? Does it work like does in humans? Or, like Leanan's theory suggests, do they have control over their reproductive systems?