The genetics of addiction

[Meggie]

Hi all, my son looks a lot like my brother. It is uncanny! My brother, unfortunately, has struggled with opiate addiction for about ten years. Does the fact that my son shares a great number of physical traits with his uncle mean that he is more strongly predisposed to addiction than, for example, my daughter? Than the average person?

[Delta1212]

The fact that your son is related to your brother may mean that he is more likely to be more predisposed to addiction than the average person... But that's a lot of maybes. For one, you don't know if your brother himself is actually predisposed toward addiction. You don't have to have a strong genetic component to struggle with addiction, although it certainly doesn't help if you do.

 

For another, a physical resemblance doesn't mean they share all of their genetics. On average, your son probably shares about 25% of his DNA with your brother, give or take a few percentage points. So does your daughter. You share even more. So a genetic predisposition toward addiction in your brother is more likely to indicate it's presence in you than in either of your children, regardless of appearance. And if it's not present in you, it isn't going to suddenly crop up in your son just because he looks like your brother (unless his father's side has it's own addiction issues).

 

Basically, just because two related people look alike does not mean that they share all of the same genetic material, and certainly doesn't mean they are more likely to be predisposed toward the same things than anyone else in the family, other than, obviously, looking a certain way.

 

But again, having an addiction problem doesn't necessarily mean you have a genetic predisposition to addiction, and having a genetic predisposition toward addiction doesn't necessarily mean you're going to suffer from an addiction problem. If you're really concerned, you could probably get some DNA testing done on your children, but either way the real deciding factor is going to be more down to whether they get involved with substance abuse in the first place rather than how disposed they are toward getting hooked once they've taken the plunge, and that's going to be down far more to education, environment and, frankly, luck than it is to DNA.

[CharonY]

One should also note that addiction is a complex condition, with genetic as well as behavioral aspects. There is not one thing that determines it. The genetic basis would for the most part determine how strong drugs would affect you at a given dose, yet that alone does not mean that you would become an addict (e.g. if you do not come into contact with the drug in the first place).

It does not mean that your brother actually has any genetic reasons for being susceptible to opiate abuse in the first place.