Can someone give ELI5 explanations for two more questions? (1) Your body has to create brand new stem cells for your baby, right? Why can't we do this same pro

Can someone give ELI5 explanations for two more questions? (1) Your body has to create brand new stem cells for your baby, right? Why can't we do this same procedure in the lab? (2) When stem cells are injected, how much does it matter if it's your own stem cells, a relative's stem cells, or a random person's stem cells?