Questionable at best. Unless you're positing he just spunked into the those incubation chambers. By your definition, all Space Marines are his actual children.
I mean emotionally. He clearly does not care about all SMs in the same way as the Primarchs, and the Primarchs are also "natrual" instead of augmented.
The progression goes: Thunder Warriors (Damn I need these guys to last longer.) --> Primarchs (Welp, there goes like 100 years of hard core genetic science.) --> Space Marines (Guess I'll use the left overs to make these....)
This more supports my version than yours. He retained all the resources of the Primarch Project, but instead of continuing with the actual Primarchs he adopted it into an augmentation procedure and used it to make the Legions while he looked for the Primarchs.
Space Marines in general demonstrated this point already. No primarchs needed. I mean yeah, shit would have gone worse for the Imperium if 100,000 Primarchs had turned on him.....but in galaxy where whole worlds are vaped, millions killed, reality shredded....could it really have been that much worse?
The Space Marines never could have taken down the Emperor. Hell, the Horus Heresy as a whole almost failed. Only that critical point of using Horus emotionally against the Emperor allowed him to be struck down. And besides that, the Space Marines never would have had the corruption rates they did if not for the Primarchs to convince them. The HH with every Legion having the defection rates of the loyal ones would not be too impressive.
I have to say, the Emperor impressed me a lot more before I learned all the Secret Shaman Snatch lore, and he was just a super psychic human who refused to let Humanity perish and sacrificed himself to eternal suffering for mankind.
He's still like that. He watched human civilization from our infancy, and tried to be our guide. Even after every failing, every problem and corruption, humanity still eventually made it to the stars. But it all came crashing down and would never recover. Even after all that, when he was hardened by the ages of failure and decided to rule over humanity, he still believed we could become what we were meant to be.
And even after all that came crashing down, after being betrayed by his own children, he persists in deathless agony so that humanity can survive even as they make a mockery of everything he tried to create. That is sacrifice.