Even though she has some genes such as "where her nose color comes from." Or "Where her eyes color comes from." I think she's their daughter.
But not out of love.
Why else would Zira be so willing to kill one of Scar's blood?
Also when she does, the outlanders are disgusted.
Because she threatened her own daughter?
Or because she threatened the daughter of the very one she tried to avenge?
Some people tell me "Since Kovu and Vitani are the same size they're the same age so they must be full siblings." That's not neccasarilly true. A lioness can mate with two different lions and have one cub from each of them.
In this situation i think Zira mated Scar first(not out of love.)
and Chumvi next(In my theory he developed a bond with her) hence why she cares for Kovu more dispite him not having any blood relation to Scar.
You guys?