Chase never learnt anything about omegas because he was home schooled and his father (Ashley) just never touched on the subject for some reason, while he kept his omega father (koi) out of the image cause he was worried that they'll do something to him (Grayson and Stacy nearly killed him, while Nathanial did nothing when he saw the scene, so I guess I undertstoof his intentions) So Koi was forced into isolation from his kids, so he never learnt ANYTHING ABOUT BETAS OR OMEGAS expect his own gender
No, it seems he does knows the basics, but has no experience and he is convinced that Josh is a beta since no detectable smell (most of the time). And he naively believes everything Josh says.
The father was also extremely jealous of his own children, he didn't like them around Koi even before the baking experiment.

Wait.. Umm, Chase? Didn't you see that scar on Joshua's body?? He's a freaking omega! Why haven't you realize it?? Ughh