Pin-up boys are said to have “superior genes.” Their features include being tall, a small face, sharp nose and big and bright eyes.

But recent studies indicate that genes affect not only physical characteristics but also but also tendencies and behavior. If this is true, could “acquired factors” be nothing?

In a paper published online by the Science magazine (www.scienceexpress.org), researchers identified a genetic mutation that causes people to be extreme early birds, rising, say, at 4:00 a.m.

The discovery opened a window into the genetic basis of the human circadian rythm, which keeps body activities such as sleeping and eating running on a roughly 24-hour cycle, according to the magazine.

Familial advanced sleep phase syndrome (FASPS) is an autosomal dominant circadian rhythm variant; affected individuals are “morning larks” with a four-hour advance of the sleep, temperature, and melatonin rhythms, it said.

The magazine reported localization of the FASPS gene near the telomere of a chromosome.

A strong candidate gene, a human homolog of the period gene in Drosophila, maps to the same locus.

Affected individuals have a serine to glycine mutation within the casein kinase binding region, which causes hypophosphorylation.

Thus, a variant in human sleep behavior can be attributed to a missense mutation in a clock component, which alters the circadian period, the magazine said.

Researches show that early birds result from gene and that they are not a product by human efforts. It surprises people.

But what surprise us more is that more and more researches indicate that gene affects not only biological structure in human body such as human clock but also spiritual characteristics.