[adammichaelc]

It’s not just that they caught the virus, but that their immune systems are unable to defeat the virus. So, the battle remains active for life, and becomes a chronic infection.

Presumably, this would suggest that the genetic component is the susceptibility to the virus, and inability to defeat it.

[hellofunk]

Seems unlikely that virus is so prevalent to infect multiple family members that do not cohabitate but nonetheless show genetic link for BD.