Do you think it is definitely true that people with past family problems are much more difficult to hypnotize?

I do not think it is definitely true but the reason they would be more difficult to hypnotise is because people who've experienced fractured relationships often know enough not to trust just every jerk who smiles at them. Hypnosis is all about trust. Which is why to re-educate some one non-compliant with Psychology into swallowing it, we medicate them. The stuff we medicate them with used to be called Hypnotics until the Physician's Desk Reference began to be studied by the common folks too much. So the Pharmacologists renamed that category. Take a look at those drugs listed in a PDR from the 1980's and before those years.