I think what you might want to look at (if you aren't already- Sorry, I can't quite understand what your problem statement is) is the similarity between fingerprints in a given family. You would have to get separate families (at least 5 - Just ask five of your friends if you could use their families for this) and then categorize the fingerprints of each family member in that family. Then, see if most people in that family have a certain type of fingerprint.
Here's a link about fingerprint types:
How could you graph that data?
Well, two different ways.
Method #1: Make a separate graph for each family. On the x-axis, you would have the different types of fingerprints and on the y-axis, you could put the number of people in that family with each fingerprint. Then, you show whether or not there is a fingerprint trend within families.
Method #2: Repeat Method #1, but use a pie graph (circle graph) instead of a bar graph. You could show the percentages of each family with each type of fingerprint.
In the end, remember to also make a graph of the total number of subjects with each type of fingerprint. Then, if there is any family resemblance in the fingerprints, you could say whether or not it was really genetic (runs through the family) or just a general population trend (like a dominant trait in genetics).
If any of that doesn't make sense or you have further questions, don't hesitate to ask!
Best of luck!