A weakness of the atavistic form?

-Issues with methodology -Lombroso did not compare sample to non-criminal control group - if he had, there may not have been so many different features. Also likely to have non-criminals with an atavistic form. It is unclear as to whether facial characters cause offedngin or vice versa. -High cheekbones/strong jaw could have been due to poor diet/povery which again are confounding variables -Hard to establish cause and effect relationship between atavistic form and criminals due this data - low internal validity