Carl Zimmer

You inherit 50% of your genes from one parent, 50% from the other.

So genetically speaking, you're just a perfect 50-50 split between your parents.

It's possible that a couple generations back, you know, your father inherited some genes that raise your risk of baldness, but then also inherited other genes that lowered the risk and maybe sort of dominated over the other genes.

And then it was just sort of a, you know, which copies of those genes that he then passed down to you and your siblings, just roll the dice.

And so for these complicated traits, you know, you may have genes that are sort of tugging that in different directions.

You know, I've had my genome sequenced and I can see that I have certain genes that raise my risk of cancer, certain genes that lower my risk of the same cancers, you know, and do they even out?

Well...

That's kind of a hard thing to know right now because we still don't know that much about these genes.

So to end up with this pattern in your family, most of your siblings, you know, being bald and you're not, like, that's what you expect from heredity.

That does seem to be quite heritable.

The sort of genetic basis of that is really still quite mysterious.

And it's an odd thing because it's only, I guess, around 15% or so of people are left-handed.

I'm left-handed.

Well, I mean, how many generations back have you interrogated people, though?

That would be an interesting thing to find out.

Well, I think we are in the middle of a real revolution in bringing an understanding of heredity to our health.

Because, you know, it is possible now for each of us to get all of our DNA sequenced, our whole genome, for a thousand dollars, maybe even a few hundred dollars.

I mean, you have to remember the first human genome project cost about three billion dollars.

And so it's a kind of revolution like what we see in computers and phones, you know, in terms of DNA sequencing and also DNA analysis.

And we have so much data now and use computers to develop really complex models that can take on all this complexity.