if a relative developed a disease after I was born, would I be at higher risk to get it? why so?

Question

I always wondered this, but I never knew what the answer to this was. for example if my relative developed diabetes after I was born, would I be still be at higher risk at getting it. something like that. if that is true, then how does it work? sorry if I sound stupid

In: 1

Answer 1

Yes, but that’s probably not a good way to phrase it.

For simplicity, let’s assume that we’re talking about a genetic condition that develops (i.e. becomes obvious and starts messing with you) later in life, and there’s no way to test for it before it develops. Let’s say that it’s a disease that affects 1 in 1,000 people in the general population, and that the child of somebody with the disease has a 1 in 2 chance of inheriting it.

Now, when you were born, either you had the condition or you didn’t. That was just a fact at the moment you were born. However, nobody had any way of knowing this. So, if your parents asked a doctor for the likelihood of you having the disease, the doctor would have said “1 in 1,000, like everyone else”.

Then your grandfather developed the condition. This means that we now know that he had it and might have passed it to his child and thus to you. The chance that somebody whose grandfather has the condition also has it is about 1 in 4. It’s slightly higher than 1 in 4 because there’s a chance that you’ve got it for reasons unrelated to your grandfather. So now, if you ask a doctor for the likelihood that you have the condition, knowing your family history, the doctor will say “About 1 in 4”.

Of course, nothing changed for you when your grandfather got his diagnosis. Your genes are what they are. But now you have a much stronger reason to think you’re at risk of having the condition, and that can change the decisions you make from now on (such as getting regular checkups of the aspects of your health that relate to the condition).

Diabetes is complicated, but there is definitely a genetic component to it, so if anybody in your family is diagnosed with it, no matter when, then you should be more concerned about having it yourself than a typical person would be.