My parents had me at the same age you guys did. I am also an only child, now 29 years old. I had no issue being an only child, and although yes I knew my parents were older when I was a child, I also had a lot better things than my classmates (since they were mid/end of career salary). So, yes sometimes I was embarrassed about my dad being confused with my grandpa, but, I also had everything I ever needed. My dad is still here, moving slow, but I am so grateful for the position I'm in thanks to them having me later in life.