I'm as in the dark as you are, but I think Kin-Heon's mom was a kumiho not a maegu. So it's uncertain whether Kin-Heon is a half-kumiho or a maegu. Personally, I believe he is half-kumiho. He might even be full kumiho having eaten the fox bead, but has chosen to live as a human and his power hasn't manifested (yet).
Personally, I would love to see a powered up Kin-Heon. I imagine he could protect and defend them all with his powers, and protect them from all curses. Baek-Yeon has the gift of cognition and chose to live with Kin-Heon. I don't think it's only because Kin-Heon's grandfather was protective, kind and wealthy and Kin-Heon was his heir. I also think Baek-Yeon's gift allowed him to identify the possibility of Kin-Heon providing spiritual protection from supernatural battles and curses.
I thought that since the mother was a kumiho and the father was human, he was certainly born half kumiho. So there was no way he could be a maegu when he swallowed the whole bead, since he was already born 50% kumiho swallowing a whole bead would transform him into a complete kumiho.
human + whole bead = maegu (maegu is a kumiho, acquired)
half kumiho + whole bead = kumiho (maybe a manifested kumiho type)
Following this line of thought, he was already a kumiho when he had his son, so the son is a kumiho.
He thinks he is human bcs he never manifested kumiho powers, there was never any suspicion about his humanity, when in fact the bead is weakened and perhaps these powers only manifest through trauma.
Something serious threatens the family's life, since his bead may be a guardian star, as Baek's father said, his powers would manifest in order to save his family.
We will know the truth later. ╮(￣▽￣)╭
I think I agree with your spoiler theories. Something will happen that will force Kin-Heon's hand and he'll need to use his latent powers to protect his family.
I actually think that if Kin-Heon wants to use his powers, they could manifest without the trauma. His father-in-law could teach him some things and maybe he could visit a kumiho village. It's just that Kin-Heon was raised as a human, wants to live as a human and has no interest in drawing on those powers (yet). So any powers just lie dormant.
In a way, Kin-Heon being raised as a human and not believing in the supernatural (initially) was why he and Baek-Yeon ended up in a relationship. Kin-Heon always treated Baek-Yeon as a person and liked him for him, not because he was trying to profit off Baek-Yeon's gift of cognition. Even after he became more aware of Baek-Yeon's powers, he still didn't care about that. I think that's why Baek-Yeon felt safe around him.
Had Kin-Heon been raised as a kumiho, it would have changed the dynamics of their relationship. I think they would have still been attracted to each, but things would be different.
You can't live as if you were human anymore, now your son depends on your protection, and even Baek too, not finding out about yourself will put them in danger, you may find out that you could save them both too late in the future. Your bead is the guardian star, that name must mean something.
I have questions lolol
Can we say that half kumiho are born with the possibility of manifesting kumiho power or not?
And the fact that he ate the bead ignited the power he could have, making him kumiho and not maegu since then?
I saw in ch19 and 65 that Baek still has clairvoyance so it's certain that he didn't lose the bead, so he didn't lose the bead giving birth, does that mean that Yoon also has a bead and is a kumiho?
Knowing this, is Gyeon a pure kumiho blood of 2 high ranking foxes? :
Black fox Yoon (swallowed a guardian star bead powerful enough to save his life) with high ranking Silver fox?
So Gyeon might be a higher ranking pureblood than Baek?
So we'll see a pregnancy soon?
Loving this storyline.