THERE WAS some dark poetic justice to a study released this week finding that fathers over 40 were six times more likely to produce autistic children than fathers under 30. As grim a subject as autism can be, the idea that, for once, fathers rather than mothers are seen as responsible for abnormalities in children — because of age, no less — was nothing short of revelatory.

The study noted that the mothers' ages did not appear to be a factor. Moreover, it showed that for the older fathers, rates of autism were equally as high among girls as boys. Among the general population, boys are usually six times more likely to be afflicted. In cases of fathers over 40, the gender ratio for autism was even.

In other words, memo to the Tony Randalls of the world (he fathered a child at 77, remember?): You may think your biological clock can win a wrestling match against the hands of time, but the data suggest otherwise.

The real lesson behind this study may not be much different from that old maxim about having a child, which is that there's never a right time to do it. Biologically speaking, we're probably best off reproducing in our early 20s, but the economic and social realities of the last 30 years or so have more or less conspired to make that a pretty bad idea. Unless you happen to be Reese Witherspoon, young parenthood often correlates with higher rates of poverty — not to mention disenfranchisement from the cultural phenomenon of child-as-middle-age-status-symbol. If "Mommy Wars"-type literary anthologies and blogs such as urbanbaby.com are any indication, parenthood is not for the young but for over-mortgaged elites who debate the merits of sign language for babies as though it were an international policy issue.

But what about the 30s? That's no time to have kids either, especially if you're a middle-class professional who feels compelled to put in 60 hours a week to gain the economic status increasingly necessary to support a family. In households in which both partners are working, changing diapers while trying to make law partner can quickly devolve into a situation resembling hell.

That leaves the 40s, which would be a fine time to start having kids if it weren't for the fact that many women can't get pregnant at that point — at least not without the help of expensive reproductive technologies. Many men, of course, have been wise to this for years, often waiting until they're prosperous and middle-aged to begin having children with the kind of younger women who either don't want to make law partner or are willing to spend their husband's money on nannies while forging their own corporate ascents.