Don't get ahead of yourself yet, Thomas.
Let's leave your "ancestral blood line" argument/definition as the most salient aspect of ethnicity out temporarily for a bit. I will come back to address it a little later on.
Since you said ethnicity has cultural aspects to it, then now find the dictionary definition of culture. List elements, qualities, etc which are parts and parcels of it... I will help you out a bit. Most, if not all dictionaries, will list it encompassing things like language, art, religion, etc.
Just so we are on the same page. Now define Hmong. What qualities make a person Hmong?... Don't start talking about "hmong blood this, hmong parent that therefore hmong always, etc" until you define exactly what being Hmong entails first.
So let's say you work with a Cambodian dude - his mom is Cambodian, his dad is Cambodian, his grandparents, and everyone beyond, to his knowledge, are all Cambodian. But your friend doesn't speak more than three words of Cambodian because he grew up in an all-white zip code, doesn't have any Khmer friends, he eats oatmeal for breakfast, sandwiches for lunch, and steak and potatoes for dinner, doesn't attend any Buddhist or Khmer cultural event.
So another person comes up to you one day and asks "Hey, you are Asian right? So what's your ethnicity?" You say "Hmong." So then they ask "Hey what's your buddies ethnicity? He looks like a Laotian, Karenni (Burmese ethnic group), or dark skin Thai. So what exactly is he?"
So what would you say? "Oh, he's partial Cambodian, the rest is Uncle Tom."? Or "his blood is Cambodian, but he's not
really Cambodian, know what I mean?"?! Or "He's Cambodian by day, Batman by night!"
He sure as hell ain't fukkken white! If that's what you're implying. He sure as hell ain't American ethnic, because American is a national/citizenship status, not an ethnicity or race.
So is an Irish-American whose family has been in America for since the big immigration in the 1800s, everyone in their family is married to full blooded Irish, but doesn't speak one word of Irish, doesn't eat any Irish food, doesn't have an Irish clothes, are they partial Irish? Half Irish? Somewhat Irish? Maybe Irish? So if they are not full Irish, what's the other half? Dragon blood? American blood? Super Saiyan? LOL
You are an idiot. You still think that you can define the ethnicity of a person based on what kind of lifestyle and culture they live, what kind of name they have, and how many cups of rice they eat in a day.
You are just bitter. You look in the mirror, you see a Hmong person with broken English, also broken Hmong language, wearing skinny jeans and American Eagle shirt or whatever the hell you idiots are wearing these days, and you can't come to terms with your identity. And then in order to make yourself not feel insecure, you look at yourself at the ideal model Hmong person. And then to reinforce this idea, you talk and look down on others who aren't up to your supposedly godly standards of what makes a Hmong, a "Hmong". When in fact, compared to a Hmong-Lao or Hmong-Thai, you're nothing but an American-washed Asian who is barely Asian other than the fact that you eat rice. In other words, you just can't come to terms with who you are, without needing the approval and acceptance of others. It sounds like you were brought up by strict parents or strict Hmong culture and shaman religion. It sounds like you really need to get laid. lol Honestly, that's what it sounds like. Take a chill pill man. You're still Hmong underneath that Hmong-American complex. You're still Hmong even though you jam to Skrillex or whatever hell garbage music you listen to.