In humans having dimples is a dominant trait. in order for a child to have dimples

True. In order fora  child to have dimples, one parent must have them visible. 

When you are making a guess you are forming a hypothesis

That is true tge cactus as a structural adaptation to its envirinment has it leaves reduced to spines. but this doesnt mean it cant produce food it produces food because of the presence of chlorophyll in its stem