Ellie's Dad

So I've seen quite a few posts about awful parents and keep seeing Ellie's dad brought up from the Girl series. I really had no idea he was creepy or why? All I remember is Anna, his second wife is young enough to look like Ellie's older sister, I think she mentioned it in Girls Under Pressure when they went shopping. Is there anything else I missed? I didn't think he was bad as a teenager reading these books!