At my third day of a family celebration, I've been watching the genetic trends in my extended family. There is much discussion of who looks like whom. Two Asian mothers in this primarily Eastern-European Jewish family have added some gorgeous, great kids. I've been watching temperament. First I noticed that most introverts are married to extroverts. A nephew has my brothers body, his mother's face and introversion. His sister has her mother's body, a face from both parents, her father's coloration and is extroverted like my brother. The granddaughter of a bipolar man, has horrible OCD. The highly-functional daughter of a highly functional OCD man and "skinny, nervous" mom, says she has OCD, as does her nephew. People say I've got my mother's face, my father's family body (long-limbs, height, big belly, no hips, and the extroversion of most of the Shapiro clan). Many found out that I have my mom's resonant singing voice, when I chanted at the Torah. (Thanks, Mom.)
When I do an intake, I nearly always do a genogram, a clinically-based family tree that tracks temperament, as well as trauma history, attachment, and current connectedness. (See the assessment chapter of Trauma Treatment Handbook: Protocols Across the Spectrum). It's helpful to know if your client was the only introvert in an extroverted family, or if bipolar, depression, or anxiety-disorders run through the line. Clients often feel less shame about their symptoms when they realize that there's a genetic component, not personal failure, behind a symptom. If bipolar disorder or schizophrenia lurk in the line, I keep a closer watch for related symptoms. When working with someone temperamentally different than the rest of their family, we often target that sense of difference, and clear any shame that accrued. Keep watch on temperament. It will help you meet clients where they are, and spot issues that you might otherwise miss.