In the nature vs. nurture debate, people try to decide if personality traits and ideas are passed genetically, or are acquired by the child because of the environment they were raised in. I believe that both sides play a part in development, but here are some cool studies I found that support genetics being passed down.
This link leads to an article with extraordinary claims about a few sets of identical twins. In all of the examples, the twins would do very similar things even though they are separate and had never met each other in their lives. I think this is very incredible and shows evidence that a lot of personality traits and ideas might be genetic.