It is not normal to feel numb or have no feeling in the testes. You should see a doctor if it persists.
Usually the groom is expected to have normal testes, but it is not always necessary.
grow a beard and testes, three of them
The testes need to be kept at a temperature that is just shy of body temperature. The normal textbook body temperature is 98.6, the testes need to be kept at about 96.2 degrees Fahrenheit.
A normal body cell transfers to the testes and become a sex cell.
Only 3-4% of full-term baby boys have undescended testes, and half of those complete the journey by the age of three months
To produce sperm properly, the testes must stay several degrees cooler than normal body temperature. Their "outboard" location allows them to stay somewhat cooler.
AAS (Anabolic/Androgenic) Steroids can cause testes to shrink because artificial testosterone is introduced into the body which causes the testes to stop producing natural testosterone. This is called testicular atrophy, usually after someone stops using the steroid the body will start to produce natural testosterone again after this testes should return to normal size.
Testes
Treponema pallidum is not grown under normal laboratory conditions, but in rabbit testes.
"...I want them to live normal lives wout being neutered or spayed..." - What do you think a vasectomy is ! A vasectomy involves either cutting and tying of the tubes leading from the testes or complete removal of the testes themselves - either way your cat will have been neutered !
In any male animal the testes will grow to an average size during adolescence and that is normal and their size can not be reduced. If however one of your testes (a testis) has recently enlarged, you should go and see a qualified medical practitioner (A Doctor) as soon as possible. This is not normal and can have a variety of causes most of which need treatment.