I would say that any number of individuals "after the fact" are kind of weak as evidence. The very best empirical science is making a prediction of some new thing we've never seen before, and then testing the prediction.
So we don't dig up a bunch of bones and look for evidence that dinosaurs evolved into birds, we predict that if we dig, we will find something that looks a little like a dinosaur and a little like a bird, and then we dig.
I agree. Nobody would have realized that this was just a single person's story if it hadn't been pointed out. Thank you; I was almost about to add a "biological mother's profession" and "biological father's profession" field to our recruiting questionnaire, and have been spared an embarrassment.
Self-reports typically don't even count as one data point, because they're notoriously unreliable. Reports about one's childhood and motivations, doubly so. There's a reason psychology as a science is no longer based primarily on introspection, as it was in the 19th century.
Exceptions if people's self-conceptions are what is actually being studied; in that case collecting self-reports can be legitimate data-collection.
So we don't dig up a bunch of bones and look for evidence that dinosaurs evolved into birds, we predict that if we dig, we will find something that looks a little like a dinosaur and a little like a bird, and then we dig.