I think he struggles when he sees the extremes of violence his dad is sometimes pushed to...he may be afraid of becoming like that. But Rick does what he has to do to protect the group, and I think Carl will come to understand that, in time.
Lori, his mom, tried to coddle and baby him for a long time...the natural impulse of mothers, but it still annoyed the heck out of me (probably because I couldn’t stand her). I think Michonne is a better mother figure for Carl than Lori ever was.