In your quiet moments you might feel a jolt of panic that you might eventually have to move back into your parents' spare room – that is, if they haven't already sold the family home and downsized so they can go river cruising in Europe. But most of the time, you can ignore the drums of doom by partying, travelling and enjoying the fun of share housing. As is your right in your 20s. But it's all going to come to a head, and soon. The first wave of Gen Ys are now aged 32, according to the Australian Bureau of Statistics. That means they've started making babies. (The average age of mothers in NSW is 30, and for fathers it's 32.) Having a baby when you are living in a rented apartment is not necessarily a problem – at first.

I had my daughter while renting a two-bedroom unit, and it was fine. Until the rent got raised. And then we had to move because the owner was selling. And then we had to move again. So we took that road most travelled and plunged into the market, buying a red-brick unit with an "original" (read "old and grotty") kitchen. There are people who say that lifelong renting, even with children, is no big deal – hey, they do it in Paris! And everything is wonderful in Paris, n'est-ce pas? But renters in France are much better protected with lease agreements as long as five years, and slower rent rises. And sorry to bust a beloved cliche, but the Paris sophisticates who are lifelong renters do not represent the country as a whole. My partner is French and his family and friends are ordinary middle-class folk. I can assure you their aspirations to own their own home are as strong as ours. The red-brick unit we bought back in 2007 was nothing flash but gave us two advantages which are crucial for families. Firstly, we had stability. No landlord was going to pull the rug out from under us by deciding to sell with 30 days' notice. We wouldn't be in a flurry of making rental applications and packing boxes while navigating the rest of those exhausting early years of parenthood. Secondly, we had an asset for building wealth. On weekends my partner gradually ripped out the "original kitchen", knocked down a wall, painted and polished floorboards and tended the small garden until seven years (and two children) later we had something presentable. That meant we could sell at a modest profit and buy a house by the time baby number three came along. This has always been the simplest and most democratic means of financial security – it's what our parents did, and their parents before them: buy a modest piece of real estate, renovate on the cheap, and upgrade. Now that scrappy little unit is worth more than $800,000. We couldn't have afforded to buy it if we were entering the market today. We probably would have been outbid by an investor.

And that's why Gen Ys should be marching in the streets, because they won't get that foot on the first rung of the property ladder, at the moment they really need to – which is when they have kids. They won't have the chance to give their children stability and lay down the foundations of financial security, and the repercussions will go right down the line. Saving for a deposit will only get harder as finances take a hit from the costs of childcare, loss of income while one partner is on parental leave and all the other paraphernalia of parenthood. All this may still seem a way off in the foggy future for younger Gen Ys, especially those who are still in their early 20s. But biology dictates that childbearing can't be delayed indefinitely. And in the next five years, as more Gen Ys start breeding, the sleeping dragon is going to awake. The Reserve Bank, with typical sangfroid, has not been too alarmed about the effects of investor activity, aided by negative gearing, up until now. They have called for a review of the controversial policy but it's too late, even if the federal government were inclined to do anything about it. (As Treasurer Joe Hockey recently confirmed, it's not.) The number of first home buyers has reached a historic low of 7 per cent. Research by BIS Shrapnel predicts that by 2019 just 23.7 per cent of Sydneysiders aged 20 to 34 will own their home.

Gen Ys, when are you going to rise up and scream that your generation has been shafted? My bet is when you find yourself with an eviction notice, cradling a newborn and wrangling a toddler in a one-bedroom flat. And by then, you'll be too knackered to do anything about it. Danielle Teutsch is the editor of the Sunday Life magazine.