Attachment theory - early parenting/therapy

According to attachment theory, how might early parenting experiences effect a client’s relationship with her therapist?
And how might a therapist’s early parenting experiences effect their relationships with clients?

Where the therapist is seen to be an authoritative/caring figure, a client unfulfilled attachment needs in childhood may be attempted to be played out with the therapist in transference. So the client may be untrusting and angry, or they may become emotionally dependent on the therapist and be demanding of attention, or they may oscillate between the two. (Other attachment issues are available.) This process is likely to be an unconscious one, and in particular where the presenting problem has nothing to do with attachment issues, may not be recognised at first by the therapist or client. Once recognised however, they would need to be taken into consideration by the therapist during treatment as probably if not definitely contributing to or causing the presenting problem.

A therapist's own early upbringing is also important. Many people go into counselling as a career because they have their own issues that need fixing. Even if this is not the case with a therapist, nobody's upbringing is ever perfect. A therapist needs to be aware of the possibility of counter-transference with a client, and alert to what a client's transference to a therapist is eliciting in him or her. Does the therapist need to feel needed? Do they have an urge to 'fix' people rather than empowering them to 'fix' themselves? And if a client is clingy and dependent, what is the therapist's internal response - with a 'oh man up and get on with it' or a glow of warmth at being so essential? These inner responses (regardless of the professional and appropriate therapeutic response) can tell the therapist a lot about their own inner state!