Old sperm

Regular readers know how much I love being a parent.  Sometimes so much that the idea of having five kids seriously crosses my mind.  One thing that always pulls me back is the knowledge of the significantly higher risk of genetic abnormalities, etc., for the children of older parents.  One special needs child is enough.   Anyway, we know plenty about the problems that come from older eggs, but recent research suggested that there’s real risks that come with being an older father.  538‘s Emily Oster really digs into the research and finds that it is a lot more complicated/uncertain than upon first appearance:

The evidence on autism and other behavioral disorders appears less reassuring. The authors of a 2011 review article in Molecular Psychiatry combined a number of studies comparing children of older and younger fathers (this is called a “meta-analysis”). They concluded that relative to children born to 20- to 29-years-old fathers, those with fathers aged 30 to 39 were 1.2 times more likely to have autism; those with fathers aged 40 to 49 were 1.8 times more likely; and those with fathers over 50 were 2.5 times more likely. The studies used in the meta-analysis were all pretty consistent. They did not all find the same size effect, but virtually all pointed to increased risk of autism with increased paternal age.

To properly statistically control for possible confounds leads to an interesting design:

We would clearly prefer to have a study that compared children born to the same man at different times in his life. This fixes a few problems. First, since the father’s genetics stay the same among children, there is no longer a concern that, say, men who are autistic themselves have children later. Second, we avoid any concern that some kinds of dads are more likely to have their kids evaluated for autism or other disorders.

An analysis like this is referred to as a “sibling fixed effects” regression, a comparison between or among siblings. It’s been used to good effect in ananalysis of breastfeeding, for example…

Because mothers often age along with fathers within a family, if we analyzed sibling pairs with the same mother and the same father, it would be impossible to separate the effects of maternal and paternal age.

This paper does claim to separate these effects. How? The data includes half-siblings — children who share a father but not a mother.1 The authors can infer the effects of the father’s age separately from the mother’s age by looking within groups of siblings who share a father but not a mother.

That means the huge positive effect seen in the chart above essentially tells us that a later-born child of a father who has multiple kids with multiple partners is more likely to be diagnosed with ADHD.[emphasis mine] In the paper, this difference is attributed to paternal age.

Why push so deeply into the statistics here? Seeing what the data is really saying lets us think a little more about what else might be happening. Now that we know the effects are driven by differences across half-siblings, we can start asking what else — beyond paternal age — might be driving the difference. Most obviously, we may wonder whether being a child in a fluid family situation could itself have an impact on ADHD risk (as other studies have found).

Interesting!  I hope I excerpted in a way that made this reasonably clear, but you should probably read the whole post if you are interested.  Anyway, stable family situation or not, I’m still stopping at four.

Colbert on Cliven Bundy

Great stuff.

Though I’m not a regular viewer, I’m really going to miss the Colbert Report.  Jon Stewart does good work, but I think Colbert’s satire is generally sharper and smarter.  I suspect he’ll do great replacing Letterman, but I still think it’s a shame and a loss.  There’s probably a few dozen people out there who could do a good job replacing Letterman, but the Stephen Colbert of the Colbert Report is truly irreplaceable.

On a related note, here’s a great analysis of the politics of Colbert vs. Stewart via Mischiefs of Faction.


Photo of the day

Oh how I loved this gallery of daily lives of Storm Troopers:

Waiting at the AT-AT stop. (Those things are always late.) COURTESY ZAHIR BATIN

I’ll vote… sometime

The latest PackPoll of NC State student was focused mostly on wealth and inequality.  But if you download the full results, you get this wonderful gem (which I don’t know why they haven’t featured yet).


I.e., people are significantly more likely to say they will definitely vote in the primary when there’s not a specific date attached to it.  Obviously, this needs some more research, but it seems a lot like “I’ll do my homework…later.”

NC GOP vs. Science (again)

Wow– here’s a depressing (and sadly not surprising story).  Great reporting from NBC News:

Against the backdrop of the March 22 mudslide in Washington state, which killed 33 people and left 12 still missing as of Monday, geologists say the story of the team in North Carolina illustrates how America has never put forth a serious effort to learn from the earth’s past. Geology experts say science is often a casualty of land politics, as the nation fails to protect others who are unaware they are at risk from deadly landslides…

Most worrisome, she said, was the North Carolina experience.

In September 2004, Western North Carolina was hit by rains from Hurricane Frances, then two weeks later by Hurricane Ivan. Saturated ground in the mountains crumbled, as the Peek’s Creek landslide killed five people and destroyed 15 homes. It cost about $1.3 million to clean up, and $3.2 million to buy out damaged property.

 The legislature approved a program to map landslide risks in 19 western counties. State geologist Rick Wooten put a team together, using lidar, the newest technology to help detect changes in the ground with lasers. In one county, the team found more than 2,000 landslides triggered by a storm in the 1940s.

The cost-benefit on this is clearly a no-brainer:

The work was slow, taking about one year per county, at a cost of about $500,000. In comparison, a landslide in Maggie Valley, N.C., in 2010 cost about $1.4 million to clean up.

“The cost of the mapping to complete an entire county is less than or equivalent to the average home in the county,” Bauer said. “If we can save one home from getting destroyed, it pays for the mapping for the entire county.”

But, the politics…

But the geologists often encountered anxiety as they worked. Real estate agents feared that they would be held responsible legally if they failed to disclose a hazard area to a buyer. Builders were concerned that land values would fall. “A lot of what we were hearing was a lot of misperceptions,” Bauer said…

In the state capital, the program became a target. The legislator who had proposed the mapping, Ray Rapp, also had proposed legislation to regulate development in areas with a slope of at least 40 percent. Three times the legislature soundly rejected his steep-slope law, which was opposed vigorously by the home builders and Realtors associations.

One influential Republican, state Rep. Mitch Gillespie of Marion, had taped a bull’s-eye target on his office window, positioned so dead center was right over the nearby offices of the state Department of Natural Resources. He told reporters that the mapping cuts were part of a general budget reduction, but he added that the mapping was unnecessary and was being done to bolster efforts to reduce development and curtail the rights of landowners.

After Republicans took control of the Legislature in 2011 for the first time since 1870, lawmakers killed the maps and laid off the five geologists. A Republican state senator, Don East, told the Associated Press that the cuts “will get government off the backs of business and industry.”

Lovely.  We’ll get government off the backs of homeowners.  Of course, those homeowners might have wished for a little more government when a landslide wipes out their property.

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