Sisters rather than brothers make life happy?

My title is lifted word for word from a headline in today’s “Independent”. Only one change; I added a question mark, because I don’t believe it, based solely on my own experience.

“A study has found … ” – you know it’s a slow news day when that kind of first line makes it onto page 1. In the case of the Indy that’s not very often, partly because their front page is in general remarkably text-free. This story only made it onto page 14, so we can thank the G20 summit for something.

The aforementioned study says that sisters spread happiness while brothers breed distress. “People who grow up with at least one sister generally turn out more balanced and happy. In contrast, having only brothers tends to have a negative effect.”

Researchers tested the psychological well being of 571 people aged 17 to 25. They apparently found having a sister was associated with higher scores on a range of measures important for good mental health, …. e.g. better social support and more optimism.

Well, my researchers questioned only one person; yours truly. I have four brothers and no sisters. That isn’t to say I wouldn’t have liked to have a sister. In fact my sainted late mother would have loved to have had a girl, which is probably why she ended up with four boys.

However, against all the evidence of this news story, I consider myself pretty happy. In fact I’d give myself a 9, on a scale of 1 to 10. My question is this: what went wrong in my case? I think we should be told.