system
Given the following post, respond as if you're commenting on Reddit:
human
If I had my own testicles taken out and someone else's implanted in their place would my sperm have my dna? 

This is, of course, assuming that testicular transplant is possible. 

If I had my friends testicles implanted in me would I have my kids or his?
gpt
His kids.

Sperm are created from precursor cells at the "outside edge" of the seminiferous tubules called spermatagonia, which migrated into the testes at about 6 weeks gestation. No new spermatagonia are available to migrate after this point and therefore your "pool is set". You could hypothetically transfer your friends spermatagonia into your testes, but your immune cells will recognize them as foreign, and no one wants their testes swelling up due to that (opinion).