I appreciate all the responses. I'm in my mid-40's (an "older dad") and my wife is 6 years younger than me.
Here is the explanation for my risk aversion: From the mid 1990s to the early 2000s, I worked for a high-tech company that experienced exponential growth. It went from a small startup to a world-wide company with over 10,000 employees. I had approximately 120,000 shares of stock in this company. The all-time high price of that stock was $60, while my cost ranged from about $3 to $20 per share. I was ready to retire in my early 30s, but all my eggs were in one basket. The market crashed, the economy entered a recession, and the company collapsed. I didn't sell a single share the entire time - I was confident that the only direction it could go was "up."
So, I'm a prime example of how human emotions can lead to irrational financial decisions. I was irrational then (I should have harvested the money and diversified), and I'm irrational now (I'm afraid of crashing and burning again). That's why I've been reading MMM, jlcollinsnh, and other FI/ER blogs for years, but only now am I reaching out to like-minded people.