Bloodlines are a real thing in this world and it is pretty interesting how they work, they manifest themselves when you aren't "mortal" anymore when you are at peak body tempering realm. It is at it weakest then, only 10 generations before it starts to weaken with 0.1% per generation. It also exist in 4 forms, spirit; spiritual; physical and soul.
The 4 forms of bloodlines are connected towards what cultivation way the creator of the bloodline cultivated since when a new life is made the parents give up a part of themselves in these areas to create the new life.
The bloodline also helps the descendents with their cultivation in the respective way, physical for body; spirit for spirit; spiritual for spiritual and soul for soul. It makes it easier to absorb the energy needed but it also make it so they need more energy for the same thing.
If somebody has a bloodline from somebody in peak body tempering realm and breaks through to acupuncture opening realm then so will that persons bloodline evolve and become stronger but still be from the original bloodline.
Bloodlines also stay longer the stronger it is a peak body tempering bloodline can exist 10 generations before starting to weaken a acupuncture opening realm bloodline can exist for a 100 generations before starting to weaken since every realm imposes on itself 1st realm 10 generations 2nd realm 100 generations 3rd realm 10 000 generations etc.
Bloodlines is not only good though, the birth rate and probability gets weaker the stronger the bloodline is. The ratio is 1:5 between peak body tempering realm and a normal human and the ratio between a first stage acupuncture opening realm and a peak body tempering realm is 1:10. And it continue in that way.
For that reason so does most cultivators "seal" a percentage of the bloodline to be able to get children the higher the cultivation the higher the percentage needed to be sealed, a peak body tempering realm person can at most seal 10% of the bloodline before it stops working and that makes the ratio from 1:5 to 1:2.5. A first stage acupuncture opening realm can seal 11% and makes the ratio from 1:10 to 1:9.