Question

Two fathers and their two sons go fishing together. They each catch one fish to take home with them. They do not lose any fish, and yet when they arrive at home they only have three fish. How can this be?

Answer 1

Possible reasons are: The fish has been stolen. The fish has been dropped somewhere.

Answer 2

2 fathers and 2 sons
1 grandfather, 1 father, 1 son
3 people who each catch 1 fish
3 fish in total
when they get home they still have the 3 fish they caught, none were lost and none were gained. They always had only 3 fish.

Hope this helps, i tried to explain as best i could.