Genetics.
WHAT KIND OF QUESTION IS THAT?!? and yes, it is. Is your penis retractable? Then neither is a bulls.
There is no scientific evidence to support the claim that race alone determines penis size. Penis size is influenced by a combination of genetic, hormonal, and environmental factors. Variability in penis size exists within all races and should not be generalized based on race.
No. A bull's penis is made mainly of cartilage and epidermal tissue.
Bulls have what is called the Sigmoid Flexure which is a muscle that expands to allow erection for copulation, and then contracts, pulling the penis back into the bull's body during the time when the penis is not needed.
The function of the penis is for only two things: excreting urine and to copulate with a cow in order to produce a calf.
It's called a penis, just like in all male mammals, from humans to dogs to dolphins.
The size of the normal force and coefficient of friction determines the size of frictional force.
The rate at which magma cools determines the size of the mineral crystal.
You are in the category "boastful". Penis size is not caetgorised.
No, wearing underwear does not affect penis size. Penis size is determined by genetics and other factors, not by what type of underwear a person wears.
No, the removal of a man's testicles does not affect the size of his penis. The testicles are responsible for producing sperm and hormones such as testosterone, while the penis size is determined by genetic factors.
It depends on age and whether you have been through puberty yet.