Science Buddies: "Ask an Expert"

Why in the procedures does a student compare related siblings to unrelated people? How do you use the data gathered from this to make a conclusion?

Also if they found 3 siblings and 2 of them match but the third one doesn't how would you count this? A match or not? Same if they collected 4 siblings and only two of them match but they other two don't?

Hello and welcome to Science Buddies!

Regarding your second point of multiple siblings: the data analysis for the project is dependent on using pair-wise comparisons. To preserve the mathematical process, I would break the siblings into pairs. For instance, three siblings A,B,C would make three pair-wise comparisons (AB, AC, BC).

The data is "analyzed" by simple comparison. Each pair-wise "match" of fingerprint type is tallied up. The comparison is made between related siblings and unrelated individuals to determine whether fingerprint type is more commonly "matched" in related pairs than in unrelated pairs. I hope that helps!