The birth rate is hitting record lows, which has caused some analysts to express concern over the "plummet." But it may not be nearly that dire—all you have to do is talk to today's parents to find out why.

According to a new Morning Consult survey by The New York Times, most young Americans simply don't aspire to have families as large as those a generation ago.

For the nationally representative survey of 1,858 men and women aged 20 to 45, more than half said they planned to have fewer children than their parents did. This is in line with other research that's shown Americans now think the "ideal" family size is two—which is down from the 1970s when three was the average American dream, and way down from the 1930s when most wanted families of four kids.

The new survey also helps illuminate the factors that play into our decisions about family size. At the top of the list are concerns about the expense of childcare and general financial concerns, as well as a desire to have more leisure time and time devoted to the children in the family.

About half of the respondents already had children. Among those who weren't parents, only 42% said they wanted kids. Another 34% of the respondents weren't sure if children were in their futures, and 24% had no plans to become parents. Among those on the fence or planning to be child-free, the leading reasons included wanting leisure time, being unsure of the expense, or not having found a partner. But concerns about the economy, global instability, and population growth also weighed on the minds of an average one-in-five non-parents.

"I think there is far more permission to choose a child-free life than there ever has been," said "Motherhood Clarity Mentor" Ann Davidman during a recent interview with the Washington Post. "There's so much out there to help child-free women feel good about themselves, to not feel shamed."

Whether it's child-free, one child, two, three, or more, the takeaway is clear: Although we may be able to average the numbers to come out with an "ideal" number of kids per American family, the reality is that ideal truly varies from person to person—and the best thing we can do is respect that.