1) Video games have historically underrepresented women and minorities in both character representations and marketing. Female characters have often been limited to tropes like the damsel in distress.
2) More recent games have provided more options for customizing avatars and their race/gender, but stereotypes still persist in both character designs and player interactions. For example, most black male characters are athletes.
3) Massively multiplayer online role-playing games in particular can reinforce real-world biases through the social interactions between globally connected players. Representations in games both shape and reflect societal views.