Heart Attack is more inheritable than stroke

In a study published yesterday by Circulation: Cardiovascular Genetics, TheHeart.org discusses the genetic link between inherited Myocardial Infarction (MI or heart attack) and inherited stroke. While the link between MI and your parents is there, it is not an overwhelming factor (although, in my particular case, it seems to be the only factor we can determine). In stroke, it seems, it is even less of a factor.
In the study, they looked at histories of 906 people with Acute Coronary Syndrome (ACS) and at 1015 people with histories of TIA or stroke. The findings were significantly different:
In the patients with TIA or stroke:

• 21.3% had one parent with stroke
• 2.1% had two parents with stroke
• 8.1% had at least one sibling with stroke
• 1.4% had at least two siblings with stroke

In those with ACS, the results showed significantly more inheritance/genetics at work:

• 30.6% had one parent with MI
• 5.2% had two parents with MI
• 21.1% had at least one sibling with MI
• 7.1% had at least two siblings with MI

In the article, they run through the math, but here's the bottom line - if you compare people with stroke with people with heart disease, the folks with heart disease were over 5 times more likely to have two or more siblings with the same condition. They were 2.6 times more likely to have at least one sibling with ACS.
This means that heart disease has a moderate inherited, genetic factor. The numbers are so low for stroke inheritability that researchers believe there is a much smaller link - the factors that determine stroke seem to be much more environmental. This reinforces familial history when looking at MI risk - a very easy question to answer - it costs nothing and involves no tests.
So if one or more of your siblings or parents has heart disease - look for it in your own health!