The following information may help to address your question:
While it is possible that having a first degree relative with a brain arteriovenous malformation (AVM) affects your risk for an AVM, this risk is likely very small. Currently the cause of brain AVM's is not known. Likewise, the role specific genes and/or environmental factors play in the development of these malformations is not known. There have been rare reports of brain AVMs occurring in more than one member of the same family. It is not known whether or not these cases were coincidental.
If a relative has more than one AVM, or a history of nose bleeds (or more serious hemorrhage), telangiectasias, and iron deficiency anemia, a diagnosis of the rare genetic syndrome hereditary hemorrhagic telangiectasia (HHT) should be considered. Relatives risk for HHT can be as high as 50% or 1 in 2, however risk for serious events, like stroke, will vary.