My dad and me in 1979. I think I was getting an alarm clock as a gift for my first day of kindergarten.

(And on mothers and sons. But I am a daughter, so that's my frame of reference. Sorry, sons.)

I keep thinking about an article I read in the fall of 2011 in Psychology Today. By Christopher Badcock, Ph.D., it was called "The Incredible Expanding Adventures of the X Chromosome."

The article initially discusses how chromosomes are inherited and then drills down into intelligence, behavior, and autism--all of which is fascinating. I highly recommend reading the article for the full scoop. Because as interesting as the drill-down bits are, the basics of chromosome inheritance are what I keep chewing on.

Here's the deal: Everyone inherits half his or her chromosomes from each parent. The pairs are matched, except for the pair that determines whether you're born a girl or a boy. Girls have two X chromosomes, one from each parent, and boys have an X from mom and a Y from dad.

Nothing new from what you learned in high school biology, right? (Ah, Mendel and his peas.)

Yeah, well, don't worry. That's not what blew my mind. This is what did:

"The X chromosome a woman inherits from her mother is, like any other chromosome, a random mix of genes from both of her mother's Xs, and so does not correspond as a whole with either of her mother's X chromosomes. By contrast, the X a woman inherits from her father is his one and only X chromosome, complete and undiluted. This means that a father is twice as closely related to his daughter via his X chromosome genes as is her mother. To put it another way: Any X gene in a mother has a 50/50 chance of being inherited by her daughter, but every X gene in a father is certain to be passed on to a daughter."

Woah. So... the daddy's little girl thing is more than just a cultural/social concept? There might actually be a genetic/biological basis?

Who are you most like, do you think? I've always loved and admired my mother to death, and wished I had many of her qualities. I've long known that I am most like my father, though. That's a good thing, too: He's a wonderful man. Our personalities are very similar. We are introverts. We don't like a lot of fuss. We don't crave public attention. We're not flashy. We are readers. We are nurturers--lovers, not fighters. We bite our fingernails. We have sweet teeth that forever doom our diets. We are sensitive--sometimes overly so.

I could go on.

That doesn't mean Dad and I have always been like peas and carrots. (Aha! An unintended Mendel pun! I’ll leave it in.) Over the years, we've had times when we have been painfully frustrated with each other. But sometimes that happens with people who are so very much alike.

The article goes further, into grandparents. Think about it: Where did Dad get his X chromosome, the one he passed down, intact, to me? From his mom. Of my grandparents, I am most closely related to my paternal grandmother.

No wonder I look so much like her. This is what I'll look like when I'm 82:

Gladys Farnsworth (nee Kennedy) c. 1992. Aged 82.

That does mean, though, that I am least closely related to my paternal grandfather.

Flip this for boys. Boys are most closely related to their maternal grandfather. The paternal grandmother and grandson have no sex-chromosome relatedness, because the X that grandmother passed on to the father wasn't passed on to the grandson. And that means that boys are more directly related to their mothers. (Hence, then, the mommy’s boy paradigm?)

So that's my story. And yours. Who are you most like, do you think?

Dad and me in September 2011, at my brother's wedding rehearsal dinner.

On Dads and Daughters