You’ll see various theories for this aspect of feline behaviour. In general, domestic cats are indeed reluctant to be petted on their stomach. I want to try and answer the question because the National Geographic’s reason is that the hair follicles on the belly and tail are hypersensitive to touch.
This is incorrect in my opinion. Many cat owners observe their cat presenting their bellies to them to be petted so it can’t be said that all cats dislike being petted on their stomach. It depends on the individual cat and the relationship between cat and human.
The reluctance or caution comes about because when the domestic cat’s belly is facing upwards a cat is in his most vulnerable position. For a human hand, at that time, to come forward towards the belly and make contact with it goes against the grain of the innately defensive character of the cat who is primed for survival in the wild. That feeling of self-preservation is not removed by being domesticated and living in a cosy and secure human home. It is fixed in the cat’s DNA just like the ever-present desire to hunt even though the cat is not hungry.
A very trusting cat will go belly up and allow her belly to be gently rubbed. This is when domestication overrides the wild cat within.
But that wild cat within is always near the surface and is never removed from the domestic cat’s personality which leads to this apparent dislike of belly petting.
And, finally, belly petting needs to be gentle as we all know, although some individual cats can tolerate more. This is because the belly of the cat is petted less than normal resulting in the cat being less acclimatised or habituated to it and is therefore less tolerant of it. The threshold of tolerance is lower than for a cat’s cheeks and shoulders or flanks for instance. Secondly, it is not axiomatic that domestic cats like being petted. Humans do it as much for themselves as for their cat. Domestic cats like it to a point and to varying degrees. There is a limit in all instances of cat petting from the cat’s perspective.
SOME MORE ON PETTING: