Much of our relationships (be it romantic or platonic) online revolve around how much we can relate to another person. Similarities are a foundation of relationships. Similarities take the form of culture, upbringing, family situations... and age.

Off of the top of my head, take a look at the song The Babysitter's Here by Dar Williams (who is in her early 30s).

Tonight was just great, she taught us the sign for peace
She sits on her hair and she's tall as my dad
And she tie-dyed my shirt, and she pierced her own ear
And it's peace man, cool yah, the babysitter's here
He wears an American flag on the butt of his ripped up pants
The images in that song will be instantly recognizable by anyone who was born in the 60s, and especially if you can remember the Summer of Love, even as a young child. There are some ideas there that I just can't relate to - my babysitter never said 'peace man'. While my parents were married under a peace flag, it just doesn't hold the same symbolism for me as it did for people who were born earlier - I can't relate to them as much.

Another song that pops into my head is Leningrad by Billy Joel.

I was born in '49,a Cold War kid in McCarthy time
Stop 'em at the 38th Parallel, blast those yellow reds to hell
Cold War kids were hard to kill under their desks in an air raid drill
These are images from a time well before mine, and I only have glimpses into the emotions and thoughts of that time through the media - I have no actual recollections of that time myself.

Likewise, there are people who can't relate to the images of my youth. Cosmos on PBS - the music still makes me think of it. Meanwhile, my little sister finds the music 'cool' but it doesn't stir up any memories of her youth. And I am certain that there are memories hiding in people many years my senior that don't touch me as strongly as they do to others.

Billy Joel is an excellent source of historical images - just look at We Didn't Start the Fire, and ask yourself at what line of the song do you start recognizing images from your own life? No, don't answer that here - just think about it.

While it is certainly possible for relationships to span the decades, it is far easier to have a relationship with someone who you can relate to - who has lived through similar things... who is a similar age.

For the record, I'm 27 (28 29 30 now (ack - have to keep updating this node)).