When Hollywood’s golden couple, Brad Pitt and Angelina Jolie, had their first child, it was a girl. When Tom Cruise and Katie Holmes had a baby, and Gwyneth Paltrow and Chris Martin had a baby, they also were girls. Coincidence? Perhaps not. Research from the London School of Economics indicates that physically attractive couples are 36 percent more likely than unattractive couples to produce a girl as their first child.

The research, led by evolutionary psychologist Satoshi Kanazawa and published in the Journal of Theoretical Biology, is based on the study of 3,000 young American adults in 2001 and 2002 who were taking part in an investigation called the National Longitudinal Study of Adolescent Health.

After hours of face-to-face discussions, interviewers ranked the attractiveness of participants using a five-point scale ranging from “very unattractive” to “very attractive.”

Asked whether rankings were subjective, Kanazawa argued that physical attractiveness is an objective quantitative measure, just like height and weight.

“Standards of beauty are both innate and culturally universal, and everybody agrees on who is beautiful and who is ugly just like they agree on who is tall and who is short,” he said. The biggest factor is facial features, he said