The moral deliberation of someone is not free from variables he or she did not choose i.e. genes, environments since conception to the present, nutrients from conception to the present, experiences from the womb to the present. We don't have free will. We have determined and constrained will. This is why no biological being is morally culpable.
I do some things even though I don't want to do them. Here are some things I have done, currently do or will do even though I don't want to do them:
1. Breathe
2. Eat
3. Drink
4. Sleep
5. Dream
7. Pee
8. Poo
9. Fart
10. Burp
11. Sneeze
12. Cough
13. Age
14. Get ill
15. Get injured
16. Sweat
17. Cry
18. Suffer
19. Snore
20. Think
21. Feel
22. Choose
23. Be conceived
24. Be born
25. Remember some events that I don't want to remember
26. Forget information that I want to remember
27. Die
My definition of free will is a will that is free from determinants and constraints. To prove me wrong, you would have to do the following:
1. Live forever without consuming any oxygen, fluids, or food.
2. Do things other organisms e.g. tardigrades, dolphins, chameleons, etc. can do.
3. Teleport everywhere and everywhen.
4. Prevent all suffering, inequality, injustice, and deaths.
5. Make all living things (including the dead ones and the never-born ones) forever happy.
6. Be all-loving, all-knowing, and all-powerful and make all the other beings also all-loving, all-knowing, and all-powerful.
7. Own an infinite number of universes and give all beings an infinite number of universes each for free.
Once you have done the above tasks, I will be convinced that you have free will. If I had free will, I would have already done the above tasks.