Turning to Crime - Biology - Evaluation (3)
B & W+D - These studies weren't experimental in that the researchers didn't manipulate the IV... results are , simply correlational. So in Brunner's study, this only suggests a link between a gene mutation and aggressive behaviour.
We can talk about "tendencies", "likelihoods" and "probabilities" but you can't say X Causes Y.
Remember Correlation DOES NOT EQUAL CAUSATION!!!