The one who downvoted......
Fight me!
Then how was taeju born? Σ(っ°Д °;)っ
Wow at same time(￣∇￣")
Magic
Omegaverse doesn't have strict rules aside from the major a/o/b, pheromones, bonding, etc stuff. Every author can tweak the settings as long as the overall general things remain. Some stories have male betas and alphas who can give birth, some have it so that bonds can be surgically removed and are not forever, etc., so it's not strange that in this story two alphas had a kid.
Σ(っ°Д °;)っ
(づ￣ ³￣)づ
The author confirmed that taeju's dads are both alphas <3