Human behavior is difficult to study for ethical reasons. one famous experiment attempted to determine if a fear of snakes was an innate or learned behavior in humans. suggest a way that this question could be answered.

Perform a study with a large group of children that was never exposed to snakes. Show them snakes and if they are afraid, it means it was innate because they were never influenced to be afraid of snakes, but if they are not afraid it means it is learned because they are only scared if influenced by people to be afraid of them.

Ethics in regards to human experimentation would most likely not allow you to shove some snakes in front of a group of children... However there are several options.

You should merely take a verbal survey, and just ask the children if they are afraid of snakes most would just tell you... Another would be to check the reaction of children to pictures, however this may also lead to minor ethical issues.