Is eating an apple from a tree planted right next to a granddad's tomb not permitted?

Suppose A's granddad died many years ago and was buried in the back yard. Right next to his tomb, grows a very fruitful apple tree. There are many delicious apples on that tree. Is it ok to eat these apples? There is a very high chance, that the tree obtained energy from the tomb. When the granddad's corpse decayed, it released a lot of biological substances that are good for the tree.