1. Select prepubescent boy for applicant 2. harvest "genetic material" of applicant and put it into cup/jar BEFORE hormonal therapy and other biological alterations 3. Freeze cup/jar 4. Continue applicants training and initiation. If applicant does not survive initiation process, Dispose of applicant and "genetic material" and start over at step 1. If not resume to step 5. 5. Thaw "Genetic material" 6. Acquire surrogate and impregnate with thawed "genetic material" 7. Wait for Surrogate to give birth. 8. If newborn is female, wait until childbearing age to use as surrogate for step 6 before start over at step 1. If newborn is male resume to step-9. 9. Since the newborn-male carries 50% of the "fathers" DNA. We can assume that the newborn-male has at least a +50% chance to survive space marine initiation like the father did (Assuming the process is the same) This would also apply to things like the space wolves curse of the wulfen and the blood angels red thirst/black rage since survival of this relies on the genetic composition of the marine in question. 10. Wait until newborn male's "Genetic material" is available for harvest and then start over at step 2. With this system you can gradually reduce (This is easily a yearly or more process) the chances of space marine applicants rejecting gene seed while also equipping applicants with genes that are less likely to contract crucial geneflaws. So why doesn't the space marines do this?