In most chinese novels you normally cannot get a woman pregnant that is weaker than you.
Through every cultivation advancement you refine your body and therefore change and upgrade bloodline.
Just like Shen Xi choose Yun Che due to his bloodline because she knew the other men’s bloodline wouldn’t work.
And his first child was due to the fact that his Phoenix bloodline was stronger than is dragon bloodline because he was not powerful enough. So the first daughter got strong body and a Phoenix bloodline that dominates the dragon bloodline.
Just like QY bloodline is strong in the realm but Yun still barely gets much from dual cultivation with her other then gaining some comprehension due to shared bloodline.
And why did mars make XQ so cold as to think that she is stronger than everyone else when here power is not even hers? And isn’t it that power that she got that allows her to predict the future, thats why she is scared of Yun Che. Actually all the top divine masters are scared of Yun Che.