The hypothesis that identical twins have similar physical appearances but different fingerprints, is proven to be true.
Twins have identical DNA and they cannot be separately identified in a DNA test. Despite having the same DNA and the same appearance, there usually are some slight differences between them that will enable their parents to tell them apart. As the twins age, the different environments they find themselves in will result in differences in their physical appearances.
For more reliable results, science experiment should be repeated by increasing the number of participants in each group and tabling the average results.
What do you think your observations would be, if the science project were to be repeated, only this time, by examining the DNA of the different types of twins?
Try to repeat the science project experiment, involving older participants.
Why identical twins have different fingerprints? - http://www.forensic-evidence.com/site/ID/ID_Twins.html
Twin - http://en.wikipedia.org/wiki/Twin
Why do identical twins have different heights if they have the same DNA? - http://www.teengrowth.com/index.cfm?action=info_advice&ID_Advice=70822&category=body&catdesc=Body&subdesc=Normal