First of all, let's talk about the influence of genetic factors on fingers. In fact, the appearance of fingers is also inherited from parents. If the hands of parents and relatives are chubby, then the children's hands must be chubby, just like the children's body skeleton, which is determined by the genetic information on DNA. It's already stipulated. It can't be changed. The size of children's bones and the thickness of their fingers are all related to their parents' DNA.
Secondly, whether the fingers are fat or thin is related to whether the hands are prone to edema. Some people's hands are prone to edema under certain conditions, especially obese people or people who don't like sports. Their hands naturally look chubby.
Thirdly, whether fingers are fat or thin is probably closely related to people's blood circulation system. Everyone's blood circulation system cannot be the same. To be sure, some people have a good blood circulation system, and some people have a bad blood circulation system. This kind of person's limbs are usually cold, because blood can't flow smoothly, and naturally his fingers are fat.
Finally, although the fatness of hands is determined by parents' DNA, some acquired habits will also have a certain impact on them. For example, people who exercise for a long time will have tighter hands and look thinner visually.