Two sisters can grow up eating at the same table and still describe hunger, sleep and comfort in the heat differently. Prakriti, usually translated as constitution, gives Ayurvedic writers a way to discuss enduring differences between people. It is an invitation to notice variation, not an instruction to sort a family into winners and losers.
A careful reader distinguishes a customary pattern from a recent change. Someone who has always preferred a light lunch is describing a preference. Someone who has suddenly lost their appetite is reporting new information. A constitution label should never make that second observation disappear.
For a family history, record the person's own words and the circumstances in which they spoke. A summer spent working outdoors is not the same setting as a winter at a desk. Those plain details often teach us more about daily life than a retrospective attempt to assign a dosha from a photograph.
Further reading: Indian perspectives on Ayurveda (NEIAH)