Sam being blackmailed sounds likely , but I ' m doubtful Sam is abusive towards the girls because he doesn ' t act that way with his family . It looks like sam isn ' t holding back his personality but his knowledge of what happened . Remember when he was crying in the toilets in the hospital ? Could be guilt , Gemma didn ' t have that reaction and she obviously cares for her daughter . As for the DNA tests , Gettrick has already admitted to tampering with it . Yes they only found Sams DNA , and he could be Lena ' s father , but it would surprise me to make such a reveal in the final episode as it seems pointless . Plus Gettrick did actually switch the results . To me it ' s far more likely that Gemma had an affair in 1991 and Alice ' s real father is either Gettrick or Stone .