So why do cats have tails

The cat’s tail helps them to balance. The tail helps to serve as a counterbalance when cats walk on narrow spaces such as fences or shelves. ... Even though cats use their tails for balance, if a cat's tail needs to be amputated due to an injury, the cat will soon learn to compensate for the loss of their tail

Except hold on to his or her beliefs even if there is no evidence for those beliefs.

The punnett square is the device used to predict genetics.