Not to be a buzzkill, but I completely believe the study linking age, marital status, and kids with attrition rates. Correlation and causality are difficult to break apart, but from my observational experience as an IP in helo advanced and as a now 33YO guy married with kids, there is a causal relationship.
Flight school, although in reality notas difficult as we sometimes remember, takes a lot of time and committment. Your work hours are sometimes irregular, and when you are home, you spend a lot of time studying. A wife (although there are exceptions that prove the rule) usually isn't too hot on this, especially when there are rugrats running around who want to play with daddy even though he has a checkride tomorrow.
As far as age, lets face it, the older you are, you pick up new things less well. Think about why it's easier to teach languages to younger children. Additionally, the older you are, the less likely you are to enjoy getting crapped on by an IP who's your age or younger.
These things aren't to say that a committed individual can't do it. Just realize that your road will be harder than the 23YO next to you. The stat could just as well say, "50% of 60-year-old men who enter fail to complete the New York Marathon." It doesn't mean it can't be done, just that you have to work harder, be more committed, and have a family who's committed to your success as well.