How bad is it to cherry-pick scientific studies that support your position?

Very bad, explains Ben Goldacre. He calls out Aric Sigman, a popular science writer who admitted to cherry-picking only the studies that supported his pre-existing views about day care (that it's harmful to young children).

At the end of his post, which is worth reading in its entirety, Goldacre concludes:

A deliberately incomplete view of the literature, as I hope I’ve explained, isn’t a neutral or marginal failure. It is exactly as bad as a deliberately flawed experiment, and to present it to readers without warning is bizarre.

I have a feeling that last sentence was carefully edited, and that he originally wrote a different word than "bizarre."

A new study that says gay people are coming out earlier than in the past . . .

. . . is wrong in a "new and interesting" way.

That blog post (1) explains how the study went wrong and (2) asks whether it could have possibly been right.

As to the second point, the blogger (Ben Goldacre) explains:

It’s a difficult analysis to design, because in each age band, there is no information on gay people who are not yet out, but may come out later, and also it’s hard to compare each age band with the others.

(The comments section on that post also has a lot of relevant insights.)

This reminds me of the oft-repeated factoid that "50% of marriages end in divorce." How could you ever determine whether this is true? You can observe divorces that have actually happened, but you can't possibly know whether existing marriages will end in divorce.

Even questions that seem to be about concrete, observable facts can't necessarily be answered by empirical research.

Is there more or less stigma against a mental illness if people believe it's genetic?

This article looks at the question. The most striking finding: in a metastudy of 19 studies, "18 found that belief in a genetic or biological cause was associated with more negative attitudes to people with mental health problems. Just one found the opposite, that belief in a genetic or biological cause was associated with more positive attitudes."

The writer, Ben Goldacre, juxtaposes those psychological findings with this quote from a professor of neuropsychiatric genetics, responding to research that says ADHD is partly genetic:

"We hope that these findings will help overcome the stigma associated with ADHD . . . . Too often, people dismiss ADHD as being down to bad parenting or poor diet. As a clinician, it was clear to me that this was unlikely to be the case. Now we can say with confidence that ADHD is a genetic disease and that the brains of children with this condition develop differently to those of other children."

As Goldacre observes, anyone who's been campaigning against the stigmatization of mental health disorders seems have a severely mistaken assumption about people's attitudes toward mental health. If you believe someone's behavior comes from their genes, you won't necessarily be more inclined to forgive them. You might look down on them more: it's a problem with the whole person, not just a one-time decision they made. (That may be a very simplistic way to look at it. But I'm just describing how people in general might think; I'm not approving of these views.)