July 19. The birthday of someone I know well.

I’ve been thinking about birthdays … and that was before I was told about this New Yorker commentary on keeping track of birthdays in a wired world.

So, the question popped into my mind:

How many birthdays should a semi-polite, semi-social person be expected to know? By heart?

This is what I have decided is the baseline for birthdays. Every human (except those in countries without birth certificates) should know these.

1. Your parents. (But not any subsequent spouses your parents might have.)

2. Your children. No matter what. Got to know them. Unless you live in a country where it is legal to have as many as four wives — like, say, the UAE. Talking “within reason” here. If you have fewer than 10 children (as far as you know), you should be able to spit out all their birthdays like machine-gun bullets.

3. Your siblings.  Again, within reason. If you have single-digits in siblings, you should know their birthdays.

And that’s it. If you don’t know anyone else … I’m OK with that.

Inlaws? No. Grandchildren? You’d like to think you would or could, but if you have a batch of grandchildren, and you’re of a Certain Age and your short-term memory is kinda shaky, and these grandkids have all been born in the last 10 years … No. You don’t have to know them off the top of your head.

Friends? Nope. Co-workers? Nuh-uh.  Bosses? Nah.

Now, personally … I know several more birthdays than those on the base line list I outlined, above.

At least two childhood chums, and maybe three.

At least six former co-workers, and two of them are dead.

One of my grandparents — and she has been dead for 45 years.

At least two ex-girlfriends.

Anyway, that’s 21 birthdays inside my head. I think that’s pretty good … but I have a sports writer’s facility for remembering numbers. That is, I’ve never written these down. I just expect to remember them, if necessary.

But for regular folk … if you can somehow remember your parents, sibs and kids … you’re covered, far as I’m concerned.

Didn’t Seinfeld have an episode on this? He should have.