My precious niece, a pretty little 18-year old social butterfly, is afraid of crowds.

Put her in a room that’s well-stocked with people, even strangers, and she’ll be the center of attention. But put her in a crowd where everyone’s passing her in different directions and she may just have a panic attack.

My mother-in-law was afraid of pools of water. She wouldn’t go in a lake. She wouldn’t go on a boat. She wouldn’t go near my swimming pool, and even had to take a deep breath before getting in the spa. I could practically hear her heart pounding.

Now it turns out that their parents, or grandparents, or even great-grandparents may be why.

If your great-grandmother was nearly trampled to death in a crowd, there’s a chance you will fear crowds, even if you never heard great grandma’s harrowing story.

Because scientists think that your ancestor’s memories can actually change your DNA.

That if your great-grandmother was bit by a dog and became mortally afraid of them, you stand a chance of inheriting a fear of dogs from her.

The traumatic event changes their DNA, and then passes that changed DNA to the next generation, then the next. The effect continues until your grandmother’s DNA becomes diluted by the increasing number of descendants, and so disappears.

The idea of ancestral memory – of remembering things that happened to your ancestors — isn’t new, but this is the first time it’s getting the boost of scientific proof.

Of course, like all heritable traits, it doesn’t mean that every offspring will have that genetic memory, just as not every child of brown-eyed parents will have brown eyes. Heritability doesn’t work that way.

I suspect we will find that plenty of other traits are transmitted genetically, besides disease propensity, hair texture, nose shape, fear of water, and the like.

I can’t think of any real phobias of my own. I almost wish I did so I could test the theory. I could ask my mother if she, her parents, or her grandparents were ever, say, bit by a dog or nearly drown in the Blue Hole, which was said to be bottomless.

Then I would learn something about both that ancestor, and myself.

Genetic memory, who knew?