Who is most aware of what we have carried forward with us from childhood? Our partners. Intimate relationships are the contexts where these old reflexes are most likely to emerge and even dominate our current experience.
As someone who holds a doctorate in sociology, Barbara Shapiro is an avid reader and researcher; fortunately, she also has a writing group that critiques her work and is always poised to shout: "Your research is showing!"
Keep the back story sparse and sprinkle it throughout your book instead of front loading. That way, your narrative tension will be tight instead of slack, and your reader will be drawn forward by wanting to know the story behind the story.