Final answer:
Asian Americans tend to drink less or abstain from alcohol due to a genetic variation that causes unpleasant reactions to alcohol, known as 'Asian flush'.
Step-by-step explanation:
The population group that tends to drink very little or abstain from alcohol because of a biological reaction to alcohol is Asian Americans. Some individuals of Asian descent have a genetic variation that affects their alcohol metabolism, causing unpleasant reactions such as facial flushing, nausea, and rapid heartbeat when they consume alcohol. This condition is known as alcohol flush reaction, or 'Asian flush,' and can lead to a natural aversion to alcohol among many in this group.