Now is Miro KG and Veena's son? I doubt it... I think KG and Veena go back much further than that. Remember they were all but forgotten by most if not all Eternians by Adam's day.
It really would make a lot of sense really.
He-Man IS the most powerful man in the universe... FOR HIS TIME... He aint gonna live forever, and he wasn't ALWAYS on Eternia before he was born. Who's to say there haven't been many men and women who held the title, "The Most Powerful".
And who's to say that if He-Man were pitted against his UberGreat Grandfather KG... That maybe He-Man would beat him... Don't always judge by size remember? (Not MotU related, but YODA...)
By me saying he looks or acts like he does due to his family heritage does NOT take away from his uniqueness in my mind.
He just happens to look, and sound, and have many of the same ideals as did King Grayskull. Oh and let's not forget, Adam calls upon his power, so there's an added connection.
Just like I might have as many similar traits with an ancient ancestor of mine, and as you would of yours.
Does that make me a clone of them? No... I am unique, as they are unique to themselves. But did they have influence on me today even when they have no idea of who I am? Genetically yes. Does that drive who I am today? Not as a whole but definitely in great part... You can't deny that. It's scientifically proven.
You didn't just appear on earth without any parents. Neither did He-Man appear out of no where.
You almost sound as if you DENY the very existence of your family, and the importance of how you were raised by them (if they raised you...) and how that has influence on who you are.
Be it they gave you good example, or bad, that is an influence on your character.