I completely agree that trying to find the cause of dysphoria in your parents is unhelpful.
I think this same idea used to be mentioned around gay men as well. Like gay men having distant and uncomfortable relationships with their fathers and therefore 'turning gay'.
Being gay or being trans is how you are born.
Imagine how many cis kids have had similar upbringings and relationships to you without being trans.
From my own perspective and therapy I've realised not how my parents might have created my trans ness but, really importantly, how they've affected the ways I've experienced it and avoided it for so long. It's been like the slow unravelling of a tightly screwed up piece of paper.
I was raised and nurtured in a very masculine environment with a very masculine father, who was also full of love, and an overly mothering mother. My gender lines were massive! Through therapy I can see how the dysphoria I was experiencing at early ages was suppressed, and the reasons why. I can also see how my own 'trigger', at around 12-13, was actually inevitable. That led to the shame and denial years common to so many, but also to where I am now.
I would be worse off without understanding how my parents relationships shaped my and my life choices (they did!) but they didn't make me trans. I would be wary of a therapist who is trying to suggest this (based on my own understanding but also from reading so many others' stories).
Good luck with your own journey!
X
Ps: if you feel your therapist is trying to help it might be worth explaining or showing some of these responses. My first therapist was a gender specialist but my second, and to me the most helpful, is not. The second has learned about trans* by working with me but the frameworks used have been what has been most helpful. Not saying a gender specialist is not the best kind of therapist btw! With the specialist experience and knowledge they bring, how could they not be. Just suggesting that, if you do want to keeping working with your current one until you move, it could still be helpful.