My parents aren't readers. Neither of them have picked up a book for quite some time, except maybe when they drop by the library for me to grab whatever I've ordered through the interlibrary loan system. I always thought I just happened to read a lot because I'm generally quiet and shy, and reading tends to go with that territory.
I can think of two possible explanations for this. The first is that perhaps similar personalities tend to have similar interests - reading, in this case - and so it makes sense that people in one family would tend to have much of the same hobbies. In this way, reading would sort of be like something passed down through the generations.
The other explanation is that parents who read or used to read are more likely to want their children to read. To me, this one may be more plausible. I distinctly remember my mom bringing me the library every weekend all through preschool and elementary school, and since reading was something I always did, I just never stopped.
So what about you? Do your parents read? Why do you think reading tends to run through families?