We rent, we share homes, and we couch surf, but we’re not buying. The question is why?

Millennials are coming of an age to hit milestones of adulthood such as purchasing a first car, getting married, starting a family, and purchasing a first house. Conditions are favorable to home ownership such as historically-low interest rates and affordability. Yet, we aren’t biting.

First-time homeownership is down nationwide, which isn’t good news for the housing market or our national economy. First-time homebuyers comprised over one third (38 percent) of home purchases, but that is below historical averages. There’s also been a 22-percent drop in first-time homebuyers from 2009-2011 compared to 1999-2001. The most recent recession is a huge contributing factor, but now that we’re “out of the woods” first-time home ownership still lags. Millennials are wary of taking the plunge.

The Washington Post reports a study by the Harvard Joint Center for Housing Studies which questions why young people are staying out of the housing market given the affordability of homeownership. For example, looking at the Washington area the study indicated that that 44 percent of renters ages 25 to 34 could buy median-priced homes. (The study put this at $378,050, with an estimated monthly ownership cost of $2,129.) Yet, of overall homeownership in this area, just 34 percent of the homeowners are ages 25 to 34.

The conclusion is it’s time for us to get off our parents’ couches and go buy a home.

If only it is that simple.

Here's more from the report:

Many demographic and economic forces are constraining the transition to homeownership for renters in their 20s and 30s. The first is the fundamental mismatch between incomes and prices as shown in this analysis. Even in the metros where the majority of renters 25-34 could afford monthly homeowner costs for the median home, more than one-third of renters in this age group cannot. Real renter income for households aged 25-34 remains at some of its lowest levels in more than a decade. The unemployment rate for this age group peaked above 10 percent in 2010 and stayed above 7 percent throughout 2013. Also, as we indicated in our recent State of the Nation's Housing report, an additional 2.4 million households in their 20s and 30s were living with their parents in 2013 (than if the share living at home had remained at 2007 levels). Aside from covering monthly homeowner costs, unemployment and income stagnation mean that even in the lowest-cost metros in this analysis, many potential buyers cannot afford at least $5,000 for a 5 percent down payment. Finally, 39 percent of 25-34 year old households have student loan debt and often allocate a larger share of their monthly income to student loan payments than older households. As the economy improves, however, there should be more willingness and ability by these households to become first-time buyers.

This survey highlights the serious financial restraints Millennials face, but still misses important nuances. According to Generation Opportunity’s monthly jobs report 15.1 percent of Millennials are out of work right now. (In full disclosure: I work for GenOpp.) This is higher than the reported unemployment rate because it’s the effective unemployment rate, which counts discouraged workers who have dropped out of the job market. Some 1.9 million young people fall under that category. Purchasing a house is not their priority and neither is it a priority for those who are underemployed – working less than fulltime because it’s the only employment they can secure.

When you consider that even those with stable incomes have to struggle under the weight of student loan debt, it creates a compelling explanation.

Then there’s the psychological impact of these factors. I suspect that Millennials are experiencing some trauma. Given how quickly a job can be lost or your financial position changed, many young people are far more cautious about entering into a 15-and 30-year commitment to a property. Homeownership ties one down to an area which may not be appealing to a generation that is so transient. That's not to say we won't settle down, but perhaps not anytime soon.

Millennials are like no other generation –especially not like our Baby Boomer parents. They had less debt and more opportunity than our generation and that afforded them security and stability. As the economy improves, we’ll see if these attitudes change or if this is truly a lasting generational shift.