For most women, it may be all downhill from here.

Men, from age 20 to age 50, generally say they prefer women who are either 20 or 21 years old. This data comes from what men say on the dating website OkCupid.

This detail was revealed in the book "Dataclysm: Who We Are (When We Think No One's Looking)," written by Christian Rudder, cofounder of OkCupid.

"From the time you're 22 you'll be less hot than a 20-year-old, based on this data," Rudder said at a recent talk, according to FiveThirtyEight. "So that's just a thing."

That data shows that men of ages between 20 and 50 answered with either 20 or 21 as the age of the women who look best to him. The exceptions were 26, 36 or 50 year-old men who said 22, as well as 43- and 48-year-olds saying 23 and 45 year-old saying 24 year old women. That means the other 26 out of 31 age groups prefer the younger 20- and 21-year-olds. No men aged less than 50 choose women older than 24.

Rudder states in the book that it is the opposite with women's answers. They say that they prefer men who are roughly their age, with women from 20 to 39 desiring men who are only one year younger than they are. The disparity of ages never becomes drastic, with women aged 50 seeking men who are 46 years old.

Since this data comes from OkCupid, Rudder notes that these are only preferences that people state, and not necessarily who they message on the site or who they are actually dating.

"This is just measuring people's opinions, not what they actually go out and do," he told NPR. "What you see when you actually look at what people do, you see the realism set in. So these 40-year-old guys ... the people they actually have the courage to actually go out and message are a lot older: it's 30, 35-year-old women."

You can read more about the data and insights from the book at Dataclysm.org.

"Dataclysm: Who We Are (When We Think No One's Looking)" by Christian Rudder was released in hardcover on September 9.

Photo: Nick Page