She has the old king’s soul not his blood so none of her kids will be affected by the illness.
What she said
No, yona's child will not be affected by the illness. Cause she herself is the reincarnation of the king' soul when so won is the direct blood line from the king. So the illness will affect so won and his lineage
but the illness is due to the King's bloodline? Meaning now that she is the "King", her descendants gonna suffer the same thing the previous king's bloodline did. I think this is like the drawback of having the power to control the dragons.
The crimson dragons descendants suffer from this disease because they have his blood. It's passed down. But Yona won't have something like that because she isn't the crimson dragon by blood. She is the crimson dragon because she is the reincarnation of the originals soul. Not blood. So her ancestors won't suffer the same fate because she isn't connected to the original crimson dragon by blood.
but damn the story of the previous generation was so passionate.
Also, this is just a theory but I guess Yona will...
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decide not to have any children. the children of the Crimson King all succumb to illness - if she has children its gonna be like the previous generation repeat again...