Though the Research by Vernon at the University of Western

Though the research by Vernon at the University of Western Ontario and Jang at the University of British Columbia showed that attitudes toward things like reading books and participating in organized sports showed the greatest heritability rates, the researchers cautioned that:

A) the study has yet to be replicated with other sets of twins in other parts of the world.
B) their sample was small and unique in that the participants were raised in a community that had a significant number of opportunities for participation in a wide array of activities.
C) it's not likely the case that specific genes cause these attitudes but that certain characteristics make individuals more likely to prefer these activities.
D) not all behaviours are directly affected by genes as was the case for the behaviours studied in this study were.