The answer lies in . You choose your friends, your lovers, and your colleagues. You do not choose your family. This lack of choice creates a pressure cooker. You are bound to these people by blood, law, or obligation, even when you despise their politics, their parenting style, or the way they chew their food.
Characters should dance around certain "taboo" topics that everyone knows not to bring up. The tension built by what characters don't say is often more powerful than what they do say.
There is an old saying in storytelling: "Happy families are all alike; every unhappy family is unhappy in its own way." Tolstoy wrote that over a century ago, yet it remains the guiding principle for some of the most compelling narrative fiction today.