According to a new study, when it comes to choosing a sexual partner, men of all ages fantasize about one type of woman: the 20-something female.

Researchers from Finland surveyed 12,656 men and women aged 18 to 49 in an attempt to study age preferences in sexual partners. They asked each participant about which age group they were most sexually attracted to during the last 12 months and which age group they actually engaged in sexual activity with.

Just as the researchers hypothesized, the results varied by gender. Women tended to be interested in men who were similar in age or slightly older. Specifically, women in their late teens and twenties prefer male partners who are about four years older, and the age gap preference lessens as women get older.

Men tended to be interested in one single age group: women in their mid-twenties. This held true even in younger men in their late teens or early twenties.

Researchers argue that both male and female age preferences have roots in evolutionary biology. They hypothesize that women go for older men due to the “resources” they can offer, including the ability to help with offspring: “Men mature later than woman and in our evolutionary past, raising human offspring to nutritional independence necessitated bi-parental care.”

The researchers also believe that men’s sexual preference is shaped with offspring in mind; specifically, they are interested in women who are fertile.

“The highest fertility has been estimated to occur in the mid-twenties, with a decline after the age of 35,” the researchers explain. “Especially for short-term mating, men show a high interest in fertile women, that is, women in their twenties.”

What about the researchers’ second question, which sought determine if males and females are engaging in sexual activity with partners in their preferred age group? Again, the results differed by gender.

“While women reported similar patterns of sexual interest and sexual activity with regard to men’s age, men reported dissimilar patterns of sexual interest and sexual activity with regard to women’s age,” the researchers wrote.

This study was recently published in the journal Evolution and Human Behavior.